Seth Rollins. He needs to win and reestablish himself as the top guy. I understand the current situation of Brock being champ and Roman already penciled to challenge him. So the only two scenarios would be for Brock to drop the title to someone else before hand. Or to have Seth jump shows to Smackdown and give them another star to cover the absence of John Cena.
Other than that if AJ drops the strap before the rumble id like to see him win the Rumble and become a 3 time champ.