I don't know how many other people feel this way, as map size could potentially change an opinion on this...
But influence yields too much power. It takes far less effort to conquer using influence, and if you put resources into it early enough you can establish dominance early on.
For example, on a tiny map I was able to win solely using moderate-high levels of influence within 56 turns against a custom faction with moderate gearing for influence. Even in larger games I notice that influence is more important than warfare for territory control, and that conquest is near pointless as (i) If you conquer a planet that isn't in your influence, it flips back quite readily. (ii) To retain the planet after conquering it you must extend your influence to retain it so therefore you might as well just conquer by influence which currently is easy.
I'm not sure why this is out of whack, I simply feel influence is playing far too large a role. Perhaps if a planet is conquered, it should exert out a burst of your influence to at least culturally separate it (temporarily or otherwise) from the faction you are against. Maybe its just my play-style but it seems like 1 culture center per 2 planets is enough to overwhelm the AI, and the rate which culture presses borders is horrifying quick.
Thoughts, opinions, suggestions?