I reckon my all-time choice for best game ever, in terms of nostalgia and gameplay, will always be Wizball on the Commodore 64. Sensible Soccer on the Amiga was also a massive massive part of my young life. :)
I don't have a console or a game-capable PC myself these days, so the only game I play regularly is KSirtet (Tetris clone); but sometimes at my brother's house I'll be dragged into an hour or so of Winning Eleven or EA Skate when the guitars get put away and the beers come out.