RTS with a good AI?

[bovi]

Age of Empires III AI is very good at getting up a quick army, but completely moronic once it gets smacked around a bit, and requires constant supervision to be of any use at all to a team. Playing MP with an odd number of people with similar strength makes it really hard to make a match, as on hard it's practically useless and on expert it gets double the resources of everyone else so is impossible to beat.

For good turn-based AI, I can vouch for Galactic Civilizations II. Give the AI a couple of percent more income than you and you'll have a good run for your money. I also like Civ4's AI, although it tends to be very unforgiving about the wars against me, which I didn't start I might add. There's also Igowin which is not entirely stupid.