How Aggressive AI influences the game in practice?

I'm quite good at wargames, I played UG: Civil War. Which difficulty level would you recommend me to use?
- I don't want to cheese AI, bottle invasions etc.
- I don't want too-easy campaign, where I dominate the map
- Aggressive AI seems nice, but I don't want to repel zerg-rushes all the time

Which level would you recommend?