I'm not a huge fan of either but I'd have to say that Lewis is a more proven champ. Rock is undefeated and a KO machine but he has two good wins versus Charles and Walcott. Louis and Moore were ancient when he beat them. You can't blame rock for the lack of HW talent during his reign, but you can say he could have come out of retirement to fight Patterson, Liston and Johansen. Lewis's pedigree is simply better, yes he has two KO losses to B grade fighters but he did avenge them.