Depends what you enjoyed about AoE, of course... but AoE 2 was great, AoE3 was not bad, but limited...
Empire Earth 1 and 2 are SUPER to play skirmishes with, they have a really tough AI and loads of cool ages to work through. I mean, you get Mechs!
Rise of Nations is awesome too, but shorter. I like the idea of city influence for borders rather than fixed area borders... you can even play a game where you don't fight at all, just "out influence" the opponent. Also I love the idea of taking over opponent's cities instead of razing them. I used to think this was the sequel to AoE, actually, until AoE3 came along.
For more tech-based games, Supreme Commander and of course, its granddaddy, Total Annihilation.
Gotta have em all, that's the only way to be sure. :)