Which of these fighters does Jack Johnson have the best chance to beat

Depends on the rules. I wouldn’t rule him out against any of them, especially if it’s over 20 rounds and with a 1910 rule set.

 

I'd loosely take Norton, but perhaps Tunney

 

The more rounds the LESS I'd favor him over Marciano, actually

Then again I don't think Johnson is capable of beating Louis or Marciano under almost any ruleset

 

Modern rules none because his style wouldn't allow it.

 

Funny because I always thought that Johnson would be a nightmare for Rocky to face under 1900s rules. His defensive style and physical strength would be probably too much for Marciano.

 

Feel the same way.

 

The chance? All of them. The only one I'd favor over him with a high degree of confidence is Louis. Dempsey might starch him early, or he might be greatly frustrated and clowned by him. I think Johnson neutralizes Tunney pretty handily at his own game and keeps Marciano from ever getting off, gliding to a boring uneventful UD. (Then again Marciano might really bust Jack up on the inside. That fight would either be really boring or really interesting.)

 

Marciano has more stamina and is physically stronger than Johnson. Johnson would find he can't take a bull by the horns

 

I think Johnson goes 1-4 or 0-5 here. His best chance to beat would be? That would be the man who didn't like to be crowded/wrestled, had slower feet, and was there to be hit. Joe Louis. Johnson, by the way, rips Louis and does it with observation that speaks the truth, with some jealousy mixed in.

 

Johnson would have big problems with all of them except for Norton.

 

Gets destroyed by Louis, not so sure about the rest.

 

"...physically stronger than Johnson..."
He might have been. He was certainly very strong, but so was Johnson. Rock likely hit quite a bit harder despite the weight difference, but it seems to me like an open question what would happen if (when) Johnson tries to tie him up.

 

Oh I'm not saying Johnson wasn't freakishly strong, I'm just saying Marciano is moreso

Don't rule out Marciano headbutting him or blasting him out btw. I do believe Marciano hit harder than Ketchel and Choynski (again not knocking those monsters just saying Marciano hits harder)

We can't throw out the possibility of Marciano wearing down Johnson, perhaps over 25, with a body attack and activity. Johnson had great defense but in my personal opinion Marciano has the greatest stamina in the heavyweight division

I won't rule out the possibility of Johnson stealing a UD over, say, 10 rounds, but it's just hard for me to imagine