Imo, these are the best games I've played in the following game genres. I'm sure there are other games I could add to this list, but I just haven't played them.
Best RTSs: Warcraft III (RoC + TFT), Warlocked
Best RPGs: Final Fantasy VII, Final Fantasy IX, Baldur's Gate, Skies of Arcadia: Legends
Best MMO: World of Warcraft
Best Shooter: Counter Strike: Source, Goldeneye 64
Best Tycoon: Rollercoaster Tycoon with expansions
Best Action/Adventure: Legend of Zelda: Ocarina of Time
Best Adventure: Myst
Best Survival Horror: Resident Evil 4, Silent Hill
Best Platform: Banjo-Kazooie
Best Sport Games: NFL2k3, MLB with Ken Griffey Jr.
Best Simulations: Ace Combat 4, SimCity, Harvest Moon, Animal Crossing
Best Graphically Advanced Game: Crysis
Game that visually stunned me when I saw it: Half-Life 2
Game that shocked me: Grand Theft Auto III (I was in 8th grade when GTAIII came out)