My guess would be Zelda for Nintendo, Final Fantasy XII for PS2, and as others have mentioned - the most graphically beautiful Xbox360 game shown. Zelda will likely be the game of the show though in my opinion, I'd love for something we never expected to steal it's thunder though. I mean, Nintendo COULD show another useless trailer and people would be all over the game's nuts, so if it's going to be game of the show, they better have playable demos showing how different this game is from it's past installments.
/anti-zelda rant