So I've gone on my monthly starsector binge and decided to try a few unmodded runs, still as fun as I remember, so that's good.
The one thing that did strike me was that while we have some very well fleshed out factions as is, it feels like the universe is still a little too homogeneous.
Yes you have the diktat and Hegemony who are technically embroiled in a civil war and the TT corp are almost like a shadow power (small but ludicrously wealthy). I also love the Delian League vibe from the Persian League but I feel like there's something missing.
Specifically it feels like the whole galaxy is pretty much stacked up against the Hegemony (this is a similar issue with many mods) and while this does make sense in that they're technically the power in the galaxy I always feel like they should have some more natural allies.
One idea that springs to mind is another mega-corp that is allied to the Hegemony in the beginning. In my head one thing that would work would be some kind of "shipyards" entity that produces low-mid tech ships in huge quantities, they'd only need a couple of worlds and could help to explain how the Hegemony remains relatively powerful despite the opposition arrayed against them.
I think more factions that aren't interested in "dominating" the sector but simply exploiting its remaining resources or propping up larger factions could make for some interesting gameplay, especially as the player can have more impact on the sector (targeting a mega-corp producing Hegemony ships could indirectly weaken the hegemony front line, for example).
It could also help to bring the sector alive a bit more. Having independent entities that have set up vast mining networks, or specialize in exploratory missions to bring back salvage could help to add variety and life.
That being said I understand that more is not always better and anything that is created would need to be very well fleshed out in terms of the lore of the sector