NBA 2k12. Sure, it's more or less the same graphics, the same menus, the same controls and same scenario as previous games of the series and NBA Live, but I keep buying the latest installment, and I keep returning to the game when I have two hours that need passing.
That's not to say I don't enjoy and haven't played through other games multiple times, I'm rather a Bioware and Fallout sucker, but the basketball simulator is the one that never stays on my shelf for more that two weeks at a time, the one I keep returning to.