My list of favorite fighting games:
Capcom vs SNK 2
Dead or Alive 3
Guilty Gear: Accent Core
King of Fighters (pretty much any of them)
Soul Caliber II
Street Fighter 3: Third Strike
Super Smash Bros (N64, Melee, and most likely Brawl when it comes out ^_^ )
Tekken 5

My absolute favorite fighting game goes to Guilty Gear: AC. I just LOVE everything about it! Roman cancels, false roman cancels, air dashes, double/triple jumps, force breaks, etc. So many ways of defeating your opponents!
My main is Chipp, with Testament and Jam as my back-ups.