What I want from factions and in general Internal Politics is something which gives you a real challenge. I would want to see happiness being way more impactful, as of now is ridicously simple to raise it up to max values even if you are a slaver/genocidal empire (100% happiness should only be possible for utopian pacifist empires with a heavy focus on civilian economy, for example).
There's also the problem which makes always 80/90% of your pops attracted to governing ethics factions (which are obviously super-happy) but this doesn't feel right, expecially for democracies.
The idea that more happiness=more governing ethics attraction is just... Stupid, alongside many other modifiers of this kind. Having pops in your preferred factions should be a really difficult challenge, not just an automatic passive thing you get because yay.
In general, I want a far more dynamic and challenging political gameplay, with factions which change their demands based on how the empire and the galaxy evolve themselves because, for now they're just a +10% happiness (on top of all other overabundant boni of the same type) for like the vast majority of your pops.