Half-Life 2 looks awesome... of course.
Doom 3 looks great, but may be lacking the frantic gameplay of the first 2.
Halo 2 looks fun, but unless they improve on the flaws which tied the original down it may not be that great.
GTA:SA will be a steaming pile of wank. 3 was good, Vice City was Ok, but as far as i'm concerned, its gonna be downhill from now.