Joe would catch Liston ready to be beat by the time they would have fought. Frazier would grind him down and make Sonny quit. It's a question of young vs old. It would be the reverse once he would have fought Foreman. The young powerhouse bowling over the older weaker champion.....as he did in reality on two different occasions.
Still though, Foreman didn't fight many top 10 contenders previous to Frazier. He might have always had the stuff to defeat Joe.