Like, the SMB vs Deus Ex match up, this is a case of voting for Tetris on nothing but blind nostalgia.
Look, according to some, Tetris is addictive. I don't see it. I can pull out my old building blocks and enjoy myself more. Like, awesome, I can stack these blocks and build them. That can only occupy the simplest of intellects for an extended period of time.
God of War, on the other hand, is a fucking fantastic game. It's got brilliant action with some of the most satisfying combat in games, challenging puzzles, brilliant environs, a wonderfully well written story, it's even doubly awesome for Greek myth buffs, like myself, it's the recipient of over a dozen Game of the Year awards, etc., etc., it kicks ass in every sense of ass-kickery. It spawned two amazing sequels thus far and may outdo itself with its final installment. It's an incredible game, one of the best PS2 games ever, honestly, it's a game that has practically nothing wrong with it.
Again - if you want to vote for an incredible game, it's GoW. If you want to vote for nostalgia or whatever, it's Tetris. The choice should be pretty simple.