List of interesting worlds in no particular order:
[ ] Ramz: The inhabitants of this land live under constant attack from the local infestation of Orks and Grots. Oddly enough, the people here have developed a remarkable resistance to diseases - samples of their blood indicates that while they are not completely immune, plagues that will kill any other population to the last are only a temporary hindrance for them.
[ ] Paerara: A planet mostly covered with an orange colored chemical, with islands hosting the human population. This chemical is highly potent, and during the Horus Heresy some Death Guard plague marines were outright disintegrated when they made the mistake of setting foot into puddles of the stuff. Additionally, Daemons of Nurgle had been reported as outright refusing to manifest on the planet whenever the Death Guard attempted to summon them. Not so incidentally, the population seems to be extremely resistant to disease and has developed a tolerance for the airborne variant of the chemical. (Segmentum Solar).
These worlds seems greatly suited for our nurgle mission.
[ ] Rockheim: A Feral world near one of the few recorded 'Squat' realms, the locals seem to have a fairly good relationship with the short abhumans, with the latter frequently aiding the former with Ork invasions. (Segmentum Solar)
This is going on the list because the squats must live this is non negotiable.
[ ] Skullura: This planet is a Death World that complied with the Imperium fairly early on and was given the honor of being a dedicated Servo-Skull manufacturing planet. Quite likely because of the presence of the Neck Slicer Mantis, Skull Extractor Octopus, Cranium Flyers, Head Puller Gorilla and the slightly ridiculous number of other monsters obsessed with removing the head of their victims, meaning they have plenty of raw material for making the helpful little drones.
Found Khornes petting zoo.
[ ] Vladaadad: A planet continuously under attack from Chaos-affiliated pirates and Xenos. The people of Vladaadad have developed an especially cruel disposition towards the worshipers of Chaos, one that the local Forge World seems to share…. Well, you think so, given the frankly disturbing number of weapons they give the local PDF that involve impaling the enemy with a barrage of rapidly launched spikes. (Sanguine)
Potential place to put a chapter of loyalist nightlords
[ ] Kedad: A desert death world, Kedad is notable for the nearby Forge World, which houses one of the few Legio Cybernetica enclaves to make it out of the Horus Heresy in good enough standing to be exempt from the massive penance crusade that the rest of the faction has been on since the Heresy. You never interacted much with the Cybernetica, but their robotic warriors might be of use to a Chapter in their sector.
Don't want more tech lost so this is also something on the list.
[ ] Thesus: A planet composed mostly of very rocky archipelagos stretched over a vast ocean, the world of Thesus is one of the various Death Worlds that have embraced Emperor Worship, though oddly enough they seem to worship the Emperor as multiple deities - believing he was shattered into such as a result of his final battle with Horus. As annoyed as you are at their defiance of the Imperial Truth, you'll grudgingly admit that they seem harmless enough.
These guys are more on the money for the state of the Emperor then most.
[ ] Pertana IV: The most unusual aspect of this planet are its human inhabitants, who have displayed what can only be described as shocking levels of pain resistance - being by all accounts completely unbothered by even the absolute maximum amount of pain a human can survive without dying. The planet itself is mostly unremarkable, beyond the strange fog that seems to cover the entire surface.
As said in an earlier post good for tank marine maxing or for our cold shower quest