Prime Frazier & Norton weren't afraid / bothered by all of Ali's bull frap. So, Ali's edge was immediately gone. (Bonavena and Chuvalo pretty much felt the same way too).
Chuvalo and Patterson were the only 2 fighters to face ali in the 60s and 70s. Which one was the best in their eyes? There's no contest - the answer 60s Ali.
Karl Mildenberger hung in with Ali.....that was the caliber of fighters Clay/Ali was fighting at that time.
Sometimes a fighter fights to the level of the competition. And Bonaveno went the distance with Frazier, twice, and put him on his ass, and got stopped by past-prime Ali.
Still not very much action in three and a half years. Not enough to face a Joe Frazier ! Not that I'm detracting from Frazier's fine victory.
We saw peak Frazier and peak Norton, but very likely didn't see peak Clay/Ali. Stylistically, Frazier and Norton didn't suit Ali. But the speed, accuracy and sheer class of the peak Ali we never saw gets my vote over both.