Zapdos all the way. Electric types are my favorite type of Pokémon, next to Water, Ice, and Flying. It has great speed and a great special attack stat. It also looks like a force to be reckoned with (you really don't want to get it upset). I was a disappointed that it got the worst enhancements in Pokémon XD out of the three legendary birds (Baton Pass, Extrasensory, and Metal Sound).
I like Moltres next, and it has a better movepool now than it used to have. This thing is a monster:
Moltres w/ Salac Berry
Morning Sun
Sunny Day
Extrasensory
Fire Blast / Flamethrower
It gets multiple benefits from Sunny Day; Morning Sun allows it to recover 3/4 of its hp when there is strong sunlight. Moltres has the most powerful Special Attack for any Fire type, and it gets boosted a lot by Sunny Day. Extrasensory is great for it, as it helps it cover more types and takes advantage of its Special Attack.
Moltres still has a terrible weakness to Rock, though. Switch out if you think your opponent has a Rock-type attack, because it will not survive.