Not too many Dempsey would be the favorite vs him due to his faster hands and longer reach. Not to mention faster feet. I wouldn't count out Marciano, however. Sam Langford is another fighter who I think would have a good shot although Rocky would be a favourite here. The limited footage I have seen of Langford is quite good. He had the power to ko bigger heavyweights and he could certainly take a punch. Tunney would be another interesting one. Tunney faced very few legit punchers at heavyweight so I am not sure how well he could hold off against Marciano in a 15 rounder. In a 12 rounder, Tunney may be able to outbox and stay away from him, however, (And I know Tunney beat Dempsey but Dempsey had lost his speed by then and therefore, couldn't land much). It's hard to tell how well Tunney would handle a legit power puncher like Marciano. Charles is another one even though Rocky is favoured here. Louis usually weighed over 190 lbs. Schmeling was a terrific counter puncher but didn't hit extremely hard nor did he have the slickness of Charles or Tunney. I could see Max being competitive for 7-8 rounds but Marciano is heavy handed and will break Schmeling down and stop him. Billy Conn and Roy Jones could outbox him but Marciano will wear them down over the course of 15 rounds and stop them both. I don't give either of them much of a shot even though I think they could win several rounds vs Marciano. They would win rounds but slowly get worn down and tko'd.