For their era and for one PUnch it seems like Fitz has ther bigger reputation as a one punch ko artist. But if i had a time machine and matched a world class fighter against both guys.. I think they would say the naturally bigger and techinichally more proficient Moore hit a llittle harder.
Fitz Although, I think, he was the better 'puncher', as in he had more craft and intuition than Moore when it came to knocking guys out. He could really choose the exact right spots and draw men on to counters superbly. I think Moore hit harder with more force but lacked the craft of Fitz.
I think the difference between them is so little that it isn“t worthy to discuss. Both are amongst the best ever in that one.
Both were among the very greatest punchers in the sport's history. If forced to choose I would give the edge to Fitz who was just a freak of nature. His opponents seemed to concur he was the hardest around.
Fitzsimmons was a much better finisher than Jeffries, although some common oponents said that Jeffries hit harder. Some people questioned Jeffries power at the time, but nobody questioned Fitzsimmons power.