I'd suggest downloading a demo for Battle for Middle Earth (be sure it's BME 1, not 2. The second one is pretty feh.) It's a pretty entertaining game, but it isn't very complex (which may be why the AI seems more competent--it doesn't have as much to deal with). Whereas a game like EB has literally hundreds of units, BME probably has, off the top of my head, no more than 40-45 spread out among the four factions. It's a fairly simplistic strategy game, but it's one that the AI can for the most part handle without completely humiliating itself. You still probably won't be losing any games to it, though.
On the note of losing games to the AI, you might take a look at Warcraft III. I haven't played it in a while (and I never played the Frozen Throne expansion), but I do remember that I was always convinced that the AI was going to tear me apart. I don't know if that's because it gets significant resource bonuses, or because it has some of the more successful "starting tactics" programed into its operation (to facilitate rushing and the like). Just some thoughts.
Cheers.
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