I think this is a rather simple question to answer. For my money, it is Ohio State. They play Oklahoma and Penn State at home, and duck Wisconsin and Northwestern. Michigan in Ann Arbor may be a tough game, but Michigan has not defeated Ohio State yet under Harbaugh.
Alabama is second. They play Florida State in their home away from home (Atlanta) and finish at Auburn, which should be a tougher game than Michigan gives Ohio State. They host Tennessee and LSU.
Washington ranks third on my list. They have a cream puff non-con schedule. They travel to a Colorado team that loses their defense and Stanford. The biggest problem they will have is their playoff game, if USC is their opponent. Last season, a 9-0 UDub team was whipped by a 8 1/2 point dog USC team at home.