They are both crap games, neither of them was anything of revolutionary in the First Person Shooter world. Overhyped and made out to be something they are not, just like the Gran Turismo games. I had more fun with Descent than Halo. At least when it came out they offered a new style of game, the first FULLY 3d FPS game engine. Halo had, wow I can get into a vehicle and drive............blah, C&C Renegade let you do that. Graphics mean so much in the FPS world let me tell you, as if your standing still long enogh to notice, if you are go get help.
Sorry but HALO is crap and always will be. Outdated game engine just like DOOM3. All GFX and no true interaction to your surrounding enviroments.