I don't think the AI has anything to do with Pangea being considered the best map: it was (and still is for VI) the community standard and the most played map because of balance reasons: no one starts isolated on an island so no one gets to turtle and civ-city his way to victory this is especially true for multiplayer, but it's applicable to single player as well to some extent. In Civ 5 Pangea was pretty much the only good map since the AI sucked so much in open waters.