[Q]

I agree: the AI has improved a lot and uses now sea and air transports to invade weakly protected areas behind the enemy front lines.
Still the AI focus their attacks to little on normal empires and does not use the neutral empires as protection or buffer. And they do not react if a (human) empire gets so strong that they should focus all attacks on this "mega evil empire".
If the combat system will not be changed, the AI should learn the tactic human players use: let the enemy move into your firing range instead of moving yourself unless the enemy has greater range than you.
And finally if this is possible: a possibility to change/modify the AI unit purchase. This would be especially important in game types with modded units.
But once again the game has made an important progress.