Alright! Let's see if I've actually got anything to add to our expansive array of already extant pro/con lists!
Kislev
++UNLIMITED SUPPORT
+Ice Witches
+Hag Witches
+Asur, maybe
+Karak Vlag
+Neither Eonir or dwarves have a reason to particularly object to Kislev
--UNLIMITED EXPECTATIONS (this concern might be somewhat overblown; fantasy!Russians may well be culturally equipped to intuitively grasp that nothing good comes easily or quickly, even if they don't personally have the magical expertise to understand why)
-Chaos (definitely somewhat overblown as a concern - I'll explain that take in my explanation section - but still a concern)
-Karak Vlag was never that large of a Hold, and losing 1/3rd of their population from centuries of constant daemonic siege inside the Warp itself will not have improved their situation; the amount of direct support they could offer may well be limited
-If there are Asur it'll be because they had their arms vigorously twisted, which is seldom appreciated by anyone even when it isn't humans doing it to a wildly prideful elder race
Explanation: I marked Chaos as being overblown as a concern because a lot of people seem to still be under the impression that Praag has its ass hanging in the Chaos Wastes. It doesn't. It is hundreds of miles inside Kislev's borders and the only approaches to it from the direction of the Chaos Wastes run through two heavily defended mountain passes. And anything successfully punching through those passes rings alarm bells all across the Old World to muster up and head North, because everybody prefers for Chaos to get stopped on Kislev's turf rather than potentially having to fight it on their own doorstep. Praag hasn't fallen against any army that wasn't personally mustered and led by a literal Everchosen, and even then the siege took months.
It's not not a concern. But assuming that basing the project out of Praag creates a straight line pointing to desperate battles against hordes of Chaos is not warranted IMO. Further, there is no available location without serious security threats. Carcassonne has Chaos Orcs right now, and regular orcs as a constant; plus sometimes chaos cults and whatever other gribblies Bretonnia periodically farts out. Laurelorn has beastmen inside their borders. Karak Eight Peaks has an entire mountain of greenskins literally across the road. The Empire has beastmen, orcs, chaos cults, and undead inside its borders. There are, by design, no truly safe places in WHF. If Praag is more dangerous, it's a difference of degree rather than a difference of kind, and I think the degree is slighter than people have been making it out to be.
As far as actual positives, the virtually unqualified backing of a major nation-state is something nobody else is offering. Even K8P is just one Hold, and one that was very recently reestablished and none too secure yet at that. That's legitimately a big deal. If there's something somebody has that we need for the project and that somebody needs convincing, the nation of Kislev will be right there alongside us (presumably figuratively) trying to convince them to cooperate and offering them what it takes to win that cooperation. Expectation management might be a problem, but it's not like I wasn't going to keep pushing for us to boost Mathilde's Diplomacy anyway. Rehabilitating the Fire Spire just plain sounds cool to me. It's also almost certainly the case that everything that could be said about the difficulty of getting local magic experts to work elsewhere for any other option applies here. Kislev's cynicism about outsiders promising good things down the road in exchange for resources invested outside of Kislev right now is both vast and historically well-founded. For that matter, the Ice Witches literally start losing their connection to their powers if they leave Kislev, and the further they go the worse it gets. They're as enthusiastic about suffering that as you'd expect. Personally I'd rate the chances of getting them as far south as K8P as somewhere between "no" and "are you kidding us, imperinyi?"
This isn't my number one option, but it's holding strongly to second place for me.
Carcassonne
++Fay Enchantress
+Damsel hand-selected by Fay Enchantress to help out
+Neither Eonir or dwarves have a reason to particularly object to Carcassonne
+Carcassonne highly experienced in locating loopholes in chivalry's requirements
-Fay Enchantress, some of the time, when she's free, which is seldom, so really we're getting "nudges" rather than the Fay Enchantress herself
-Possible tension with Empire (again, more on this in explanation section)
-Sharing a border with the Asrai is by far the best way to be forced to deal with Asrai fuckery
-Carcassonne is highly experienced in locating loopholes in chivalry's requirements because doing literally almost anything except being a knight who hits things with dangerous bits of metal requires locating loopholes in chivalry's requirements; the novelty of this could get old very quickly
-Extremely likely to get a hard pass from Ice Witches on geographical distance from Kislev AKA the source of their powers alone
-Chaos Orcs (two not-great tastes that don't taste great together)
Explanation: Seriously, this place didn't wow me. "Shockingly enormous castle" + "shockingly tiny town" as the capital of the province suggests concerning things about local priorities to me, and the contribution we could expect to get from the Fay Enchantress seems to be getting overbilled. She is explicitly not promised to actually join the project - instead, she's noted as being extremely busy but interested in the project succeeding and willing to provide "nudges". That's not nothing, but it's certainly a far cry short of her actually straight-up joining the project. That said, a hand-picked Damsel isn't nothing either.
Regarding the "possible tension with the Empire," people seem to be regarding Carcassonne as the most perfectly neutral option. Friendly reminder that the Empire has fought multiple wars against Bretonnia. The last was recent enough that Johann's master's master fought in it, which may or may not put it within living memory. Regardless, setting up a major project that is expected to benefit a nation that has warred on the Empire in the past is the kind of thing that tends to attract a degree of side-eye, which may (or may not) become problematic.
Also, to be fully honest, I just plain don't like Bretonnia. The whole "hyperprivileged nobles ruling over heavily taxed peasants with minimal rights" aesthetic they have does the opposite of appeal to me. Here's a fun quote from the WFRP 2e book on Bretonnia: "There's one law for the nobles, another for the rich, and another for the poor. We don't bother learning the last because the poor cannot pay us."
- Louis Chamignon (nee Louise), L'Anguille lawyer
That's not a figure of speech like it would be in a lot of countries (even in WHF). Literally there are entirely different legal codes for nobles and commoners, and guess which one comes with rights. Example, same book:
Just, eugh. No human polity in WHF is a particularly swell place to live by modern standards, but Bretonnia in particular raises my personal hackles.
Laurelorn
++I AM HORNY FOR THIS LIBRARY
+Grey Lords
+"Esoteric beings" (???)
+Builds diplomatic connections to Eonir for the Empire/the Colleges
+Only ones who can actually create anything even slightly analogous to Waystones
+Tree babe (I refuse to apologize for listing this as a pro)
+Only option with realistic possibility of obtaining non-coercive assistance from Asur
-Political fuckery with Nordland/the Cult of Sigmar likely to try to draw us in one way or another
-Cult of Sigmar may make themselves particular pains due to the above
-While no one is barred from joining, the baseline comfort level for dwarves joining will almost certainly be lowest here
-Beastmen
Explanation: OH MY GOD THIS FUCKING LIBRARY. Let me break this part down a bit, because even if somebody has before it's worth hitting this again:
Caledor = Caledor Dragontamer, AKA the mage who literally created the Great Vortex. Astarielle = the first Everqueen. Yvraine = Astarielle's daughter, who became the next Everqueen. Maruviel = Yvraine's daughter, and the founder of Tor Lithanel. Just... even above those other (amazing) people, LITERALLY the chance to read scrolls personally written by the mage who created the Great Vortex that every Waystone feeds into. That is both insanely cool and incredibly relevant to our project. And the library overall is "twice the age of the White Tower." Just... hnngh.
The Grey Lords are also a Big Deal, being specifically an organization of research-focused Archmages who originally left Ulthuan because Ulthuan was being a pain about how much reseach they wanted to do (details fuzzy). And "esoteric beings"? Heck, aside from whatever they can contribute, I want to pick Laurelorn just to find out what the fuck that exactly means (I'd note that if any voters are still thinking about something like Ulgu Apotheosis, this is your shit right here). And Ulthuan is trying to build bridges with the Eonir, which means that if they wanted they could hypothetically plausibly ask for cooperation from the White Tower as a favor between elves, which IMO has by far the best chance of securing willing cooperation from the Tower of Hoeth (Teclis-senpai might notice us aaaaaaaaa).
All in all this is absolutely the Cool Magic Shit option, and I am all about the cool magic shit.
I'll note that our dialogue with Cadaeth here definitely distinctly improved my impression of her personally from how she came off in Middenheim, as well.
Also, the concerns some people have raised that the Eonir would somehow cut us out of any solution the project came up with is, frankly, paranoid to the point of being unreasonable. The Eonir have consistently been very clear that they see building ties to the Empire as the fix to the creeping extinction they've been staring in the eye for centuries. Gratuitously screwing us over for virtually no reason makes less than no sense. Especially since it wouldn't even work. The scenarios I've seen pitched for this happening are all essentially "the Eonir figure something out with the dwarves, and then they both cut humanity out." Really? Really, though? Even if you somehow think the Eonir would have a motive for that (spoiler: they actually have the opposite of a motive for that), you think the dwarves are going to backstab the Empire and Mathilde Weber? Respectively, their greatest ally for two thousand years and the force they directly credit with arresting the decline of the Karaz Ankor and changing the Time of Woes to the Silver Age, and the greatest living dwarf-friend in the entire world who is personally credited with recovering not one but two lost Holds? On behalf of elves? In exchange for, uh, nothing, AFAICT? I'm not going to say "if you actually believe that then what flavor of crack have you been smoking," but oh wait I just did.
Anyway. Not gonna lie, Laurelorn absolutely skyrocketed in my personal rankings. They're currently the leader to beat for me.
Karak Eight Peaks
++Highest likelihood of getting high-level Runesmith/Runelord cooperation
+Ability to apply BOON to its greatest effect
+Pre-existing highly positive relationship with ruler
+Only option that could theoretically be used to make the Cult of Sigmar actually be actively helpful
+Thorgrim?
-Thorgrim?
-Possibility of entire project getting actively interfered with by theoretical highest authority in Karaz Ankor, which we'd be under; concern may be overblown but we have no IC way of realistically estimating that
-Comparatively limited/difficult access to Waystones
-Cult of Thungni actively applying helicopter monitoring of any Runesmith/Runelord cooperation and glaring suspiciously at literally everyone is not likely to be either helpful or particularly welcoming to any other contributors
-Located in the Badlands, which is an accurately named neighborhood
-Entire mountain of greenskins literally just across the road, even greenskins unlikely to be stupid enough to run face-first into the same superweapon twice
-K8P fell to Skaven invasion from below once before, with a population an order (or perhaps more like orders) of magnitude larger; they haven't been seen lately, but they often aren't until they're invading
-Extremely likely to get a hard pass from Ice Witches on geographical distance from Kislev AKA the source of their powers alone
Explanation: I like K8P. I really, really do. But we've also had a really, really long time (comparatively speaking) to get familiar with K8P. Something that I came to realize in the course of the debate over which job to take is that I'm actually really ready to see some new horizons. We can maintain our home, friends, etc. in K8P while based anywhere, and I'd like to experience some new sights and meet some new people.
More objectively, the plusses here don't impress as much as I assumed they would. Better chances of Runesmith cooperation is good, but tighter monitoring by the Cult of Thungni is not. And in order to find a person better qualified than Mathilde Weber to ask the dwarves to do them a favor, Sigmar himself would have to come back down to earth. That's not even an exaggeration. Literally that's a fact; we're (distant) second to Sigmar alone in terms of dwarf rep/favor now. So if anyone can get Runesmiths to be willing to work somewhere else - even in a Tor - it's us. Especially if we drop a tidbit like "you know, it was knowledge of Waystones that directly enabled me to save Karak Vlag." Belebro can better aid us here, which would be nice, but we've got fairly expansive promises of support from everywhere else too. And it's not like he's going to say "no Boon for you!" if we pick somewhere else - we'd just get somewhat better effect from applying said Boon within K8P itself. And better cooperation from the Cult of Sigmar? Do we even actually really need that for anything? Hell, would Mathilde even accept that if she had another alternative?
Also, Belegar's whole beef with Thorgrim is a big ball of political yikes. There's other sticky political situations that the project could wind up getting tangled in (notably the Nordland-Middenland-Laurelorn clusterfuck), but AFAICT they'd be less likely to directly impact the project even if they wind up being an issue in some way.
To my surprise, K8P has wound up in third place for me.
Grey College
++Literally our home turf
+Most likely to get substantial inter-Collegiate cooperation and resources
+Hedgewise?
--Articles of Magic will make involving anyone outside of the Colleges a real pain at best, when literally the only reason this project is theoretically worthwhile is the possibility of bringing together multiple traditions
-Greatest ability for Cult of Sigmar to actively interfere, and involvement of Eonir/other foreign magic users will trigger them for both religious and political reasons
Explanation: The Articles of Magic issue is honestly pretty much a dealbreaker for me by itself. The whole point of this project is to bring in people from multiple traditions, and picking the location that will actually hinder involving almost all of them outside the Empire itself (which frankly is very much not qualified to solve this by itself) would be a counterintuitive choice to my mind, to say the least. Enhanced cooperation with the Colleges would be nice, but not as nice as what the other options generally have to offer. Especially since as a Lady Magister of good repute we're rather more likely to be able to get Collegiate resources brought elsewhere than most, even if it's more uphill than it might have been.
I'm not going to discuss the Grey College further because a), as I said the issues with the Articles are a dealbreaker for me already, and b) I honest to God intended this to be a relatively compact pros/cons list. Somebody please help me.
tl;dr - FINAL RANKINGS:
1: Laurelorn
2: Praag
3: Karak Eight Peaks
Tied for last: Carcassonne and the Grey College