I'm a huge Tetris fan, always have been. Something is just so addictive about the game, I often find myself playing it on my cell phone or on the games section of these forums. Simple, but just strangely comfortable and exciting as hell. I love the game to death.
But Doom 3 is better. In every way a video game possibly can be. The puzzle genre is probably the weakest gaming genre to exist, which is why outside of Tetris there are almost no popular other games or franchises. Doom 3 on the other hand was just mind blowing. The graphics were stunning, but the atmosphere is what really lifted the game above your average shooter for me. No game has that strange, dark kind of twisted atmosphere that Doom 3 has, it's a different kind of horror than your Resident Evils or Silent Hills.
Doom 3 deserves your vote here people. Tetris is great fun, but compared to the masterful game that is Doom 3, it just doesn't stack up.