My guess is Tom. He'll get through with what I'll call the Toadie alliance (Ian, Katie and Caryn). Ian would be smart to turn on Tom when it gets down to 5 people, but won't because he'll feel loyal to his and Tom's final 2 alliance. Katie and Caryn are just not smart enough to figure out that they don't have a snowball's chance of winning a million against any of the guys.
One caveat. If Tom and Ian decide to take Stephanie instead of Caryn, then Stephanie is the only one who could beat Tom at the final tribal council. But she would have to win the last couple of immunitys because no one will take her with them to the final 2.