I still think its Vitor. Sonnen struggled against Bisping and Belfort just knocked him out. Of course the only way to find out is to let them fight.
Chael would probably beat Vitor. Tito, Couture, Chuck, Bones. Vitor struggles against wrestlers and Chael has a crazy chin and before he got big he had unlimited cardio, I think he'd take the fight at 205 or 185 but I like Vitor's chances at 185 better due to the fact Chael was really looking bad at 185 after his suspension was over.