Gears of war 2 VS. Halo 3 VS. Call Of Duty 4?

[Wondersoftheworld]

So seeing that Epic has released some videos of the GoW 2 campaign and multiplayer... We get a slight vision of the game and what it might turn out to be. Now, which game do you think will be better and have more people playing offline and online?

Thank You, and an explanation would always be helpful.