[MaxWilson]

It depends greatly upon the pretender and scales chosen by the AI in that particular game; I have not noticed EA Arco being unusually weak in my games. Gandalf Parker has run all-AI games to collect statistics on "good" AI nations, but I don't have a link to his results. I believe Mictlan has a reputation for dom-killing itself early on.

You can fix it by using map or mod commands to give AI nations better starting armies and/or pretenders. I presume you're playing on Impossible difficulty; if not, turn it up and see if that fixes it. Also, try using Edi's BI mod. A final idea: play on crowded maps. The AIs which happen to be weak because of poor pretender choices will get eaten by those which are strong, and a "best opponent" should emerge naturally.

-Max