good question. mine would have to be

96: Diablo

97: Jedi Knight: Dark Forces 2 (sucked more time out of my life than any game since other than WoW)

98: Star craft (*ok so i lied about Jedi Knight AND WoW, this wins by far)

99: Planetscape: Torment 

00:  Diablo 2

01: Civ. 3

02: Warcraft 3

03: Call of Duty

04: World of Warcraft 

05: Battlefield 2

06: Oblivion

07: WoW: Burning Crusade (thus far at least)