Dempsey was Kid Blackie. Though he never won nothing with that name, damn serious colour line in those days.
Louis (pretty much did the lot, strong defences, weak defences, undefeated in title defences, massive continuity/commitment, awesome skills and abilities, clean role model). Ali (obviously great but hung around too long with the Spinks debacle to get number 1 place) Holmes (would have reigned longer if not for Ali and the Spinks robbery migitated by not owning all the main titles all the time) Lewis (had it all except perhaps concentration/commitment at times. Perhaps above Holmes) Johnson (since really, he was champ for twice the length he reigned, and unstoppable during that time. Come on Tommy Burns was never world champ really). Marciano (too late start as champ to get higher rating) Tyson (early demise drops him out of potential top 5) Dempsey (not enough action to rate higher) Foreman (two good career stints lift him into the greats) Sullivan maybe but his colour line dictates only partial world title owning bubbling under - Frazier, Wlad, Liston.
you mean if you could genetically meld them into one fighter? interesting. Mind you, you might end with the wrong attributes - a big lunk with a glass chin and poor skills/movement. That aint winning the Ukranian title.
1. Joe Louis 2. Muhammad Ali 3. Sonny Liston 4. Larry Holmes 5. Lennox Lewis 6. George Foreman 7. Evander Holyfield 8. Jack Dempsey 9. Rocky Marciano 10. Mike Tyson
Lennox Lewis Vitali Klitschko Mike Tyson Rocky Marciano Jack Dempsey Wladimir Klitschko Larry Holmes George Foreman Muhammad Ali Joe Louis
Ali Lewis Holyfield Marciano Louis Foreman Frazier Johnson Tyson Wladdy/Liston/Holmes (take your pick)
1. Ali 2. Louis 3. Lewis 4. Wlad Klitschko 5. Holmes 6. Vitali Klitschko 7. Foreman 8. Tyson 9. Dempsey 10. Jack Johnson