It's been years since I've played AoE II (once I got Age of Mythology, I never looked back), but I could probably help you out a little bit.
Most teams are pretty good. My personal favorites were the Japanese and Byzantines, because I loved the Samurai and Catphracts. Of course, a fully upgraded Champion could outperform a Samurai, and a fully upgraded Paladin was superior to a Cataphract in most ways. :(
Personally, I'd recommend just playing through the campaigns to get a feel for everybody. Also, the Conqueror's Expansion is a must.







