Which mod provides the best AI?

Which mod is best for improving the AI without changing the base game much?

I would appreciate answers to both of the questions above; I am planning on playing a new game with just upgraded AI, and after that a second game with upgraded AI AND other improvements as well (the base game could do with a lot of change but since I only obtained it recently I plan to play it "vanilla" for one more game before modding non-AI elements).

I am particularly interested in improving the tactical combat AI.