1. More admin. The lack of admin early and mid game is very annoying and seems to cause the AI to never have a lot of planets.
2. AI with cities. I have seen a few, but this is very few on normal. I hear of a worse situation on higher difficulty levels.
3. Some costs are outrageous. Citizens are one. Legion especially, which may be part of the reason they are so few garrisons if the AI does not choose Generals.
4. Those poor synthetics... Pop resource cost is too high. Suggested change would be half the durantium and add 1 or 2 Thulium(?).
5. Code organic races to build farm worlds on bread basket and thin atmo worlds. Both give a bonus to food. We use it, the AI should too.
6. Fix all the stupid data errors such as the bad ideology text. Is it 1pt per 2 turns or 1pt per 10? Text says one, data says another.
There are so many tiny bugs with the data I would be ashamed as a developer. Bugs are a fact of life with any software, but to leave them and not fix them is unacceptable. If you plan on doing another expansion but don't plan on fixing bugs... Well, I really like the game and I don't want to miss any future expansion or DLC because of stupid decisions...
Just my two cents.