Any of those 3 have the potential to be high graphical watermarks when this generation is through.
I'm definitely most excited to see how Santa Monica can top GoW3. The moving environments were absolutely staggering on screen. That Poseidon fight was so insane.
And of course anything Crytek does is going to be very pretty. I'd like to see them get even more ambitious with set design, destructible environments, and maybe ditching first person perspective. Imagine what CryEngine would do with a 3rd person horror game, for example.
Halo4, you can't discount it. The series hasn't delivered the most advanced technology this generation, but with a new team and a new trilogy, there's no telling what they have planned.