I want to say Chris Benoit. It makes sense with the storyline; he wins the Royal Rumble, therefore going over Heyman's head and getting another shot at Brock for Wrestlemania XX. However, I think they're just going to f>uck us over and have Stephanie McMahon come back and fire Heyman, then give Benoit his title shot, whereupon he will lose.
I say Goldberg or Kane wins the Rumble.