What I would like is the best, unaided (except perhaps from luck tweaks) on Normal Difficulty. If there are going to be any cut-down AIs, they should be reserved for difficulties lower than Normal Difficulty. The AI opponents should always press an advantage, and not leave an unguarded or weak city or output without attacking it. With regards to AI monsters, if they are encompassed in the player's territory they should attack mercilessly if they believe a city is weakly defended.