Competition wise he beat frazier (twice), norton, and foreman so he's up there pretty high. The fact that he did it with slightly diminished skills makes it that much more impressive. He would've been much better in 1970 had the suspension not happened but i still believe if he hung around til the 1980's to fight berbick and holmes after that he still would've lost. Maybe with the three more years of activity he retires earlier, doesn't develope parkinson's, and has a better record. But as you said, we wil never know.