Best RPG: FF7 (That game is Iconic)
Best RTS: Starcraft (Starcraft II when it launches)
Best Action/Adventure: Either GTA San Andreas or Twilight Princess
Best FP Shooter: Halo/Halo II Or Metroid Prime (Is MP II Echos out yet?)
Best Racer: NFS almost any one of the titles Or Mario Kart
Best Fighter: Soul Caliber (Any of the series. You just can't beat the eight way run system.) I also like the DBZ Budokai series cause I'm a Dragonball fan.(They can still do better with it though.)
I Know I'm forgetting some generas but oh well that all I can think of for now.