League for the moment, until the full Drazi fleet appears
Actualy I have played some games with my own Drazi ships already, and against my regular opponent we try to play different forces every game. But for campaign play, currently I'll stick to League, right now Brakiri & Drazi.
My personal prefernce is for the Centauri. When I first heard of the game, my buddy and I started talking about doing campaigns of Narn Vs. Centauri. He wanted Narn and I wanted Centauri. Of course we had no idea at the time how mismatched that pairing would be when the game was released.
I've always been a dedicated Fanhead; they're my largest fleet (some 150+ FA-scale ships). I also like picking up my EA and Narn fleets once in a while, but will play any of the fleets when the opportunity presents itself as they all have unique aspects and challenges in game-play.