There isn’t enough footage to make a real claim, but from my knowledge of them, it seems that Jeffries is first. He was known as the best fighter of all time during his reign (I know all time was very short at that time). Some “experts” who saw Jeffries thought he was better than boxers from decades after him. The stories of Jeffries’ workouts and feats of strength are amazing though.

Fitzsimmons I would guess would be second. Strong guy who won titles at middleweight and heavyweight. Lost to Jeffries.

The next two who knows. I mean, Sullivan basically lost and retired after Corbett. Corbett didn’t really do much with his career either. Sullivan was mostly a bare knuckle fighter.