What do you think - can you narrow it down to just 1 game?
If I had to give categories, how about:
Best Replay Value over the course of time? - God of War
Most Timeless? (if that's the proper grammar) - Guitar Hero
Best suited to be re-made 20 years from now for better graphics/sound? - Castlevania Symphony of the Night
Best Story? Legacy of Kain: Soul Reaver 2