This is mostly looking at the long-term benefits of these contacts; on a short-term basis they can all be roughly comparable to an individual psyker. It'll be once the MC becomes an established power within the Telepathica that any contacts made here can really flourish and distinguish their benefits on an organizational scale.
[] A Battleship of Battlefleet Torvum:
Meet an admiral of Battlefleet Torvum, a nephew of Sector Lord Ozmandus
[] An Imperial Guard troop ship:
Meet an ambitious Lord General of the Imperial Guard, and great-granddaughter of Lord Ozmandus.
These foster connections with the Imperial Navy and Imperial Guard, the boots-on-the-ground factions, as it were. Both are valuable as contacts since they will be the primary recipients of the vast majority of the psykers that get graduated from our programs later on. Establishing credentials and becoming a known figure would likely mean we're given preference when requests for psykers are made, and there will be at least a little bit of trust that we would provide them well-trained and decently stable psykers instead of the dregs that might get foisted upon them by more distant powers with whom they have no rapport. The weight of their organizations isn't as singularly powerful as some others, but has the inertia of ten millennia behind it and can grind a lot of issues we might face down if it means reliable assets for them. These are the options with solid general benefits when looking to the future.
[] A House Chromus Cruiser:
Meet one of the prospective heirs of Rogue Trader Lord Chromus CLVII
[] A chartered luxury transport:
Meet an intelligent Chartist Captain with connections to some of the largest economic blocs of the Torvum Sector.
These ones, on the other hand, are much more commercial and significantly more picky, with more of an eye for quality than quantity as future contacts. Incredibly lucrative to be involved with, but also likely to be much more sporadic in their need for psykers. For the rogue trader dynasty, this is just one of the many prospective heirs rather than the trader themselves, so the full weight of the dynasty's influence is unlikely to be swung in our favor except very occasionally, but if and when it does that power will be
felt. For the League, good relations with them would mean notably more regular dealings but with less influence behind them since it's essentially a merchant conglomerate rather than a megacorporation. Good options, but likely focused more on commercial/economic benefits; money is power in the Imperium too, not just how killy you are, but it's something to bear in mind.
[] An Explorator Ark Mechanicus:
Meet a introspective Arch-Magos of the Silver Rings returning home.
This AdMech connection offers potential in that most unique of things; high quality technology that can be acquired in bulk. As an explorator fleet they're as likely to have incredible lostech and archaeotech relics as the rogue trader dynasty (and are about as likely to part ways with them; only for heinous prices and with favors and assurances given), but arguably more valuable are the higher quality & better maintained augmetics, security measures, training assets, and technologies for easing psychic stability on an individual and facility basis. The AdMech has the least need for psykers in volume though, since they have some organizations of their own involved with psykery on the low end, so the requests they will extend will have to be met with likely the highest quality per-capita of any potential contacts we might make here. An extremely narrow focus in terms of potential benefits from this contact, but within that area of focus they are far and away worlds beyond what we could expect from the others.