Ali was the dominant fighter in the division over two decades when the heavyweight division had an embarrassment of riches of talent. Not just Ali, but Frazier, Foreman, Norton were all upper echelon fighters (although I couldn't stand Norton), and even the second tier guys like Ron Lyle, Earnie Shavers, Jerry Quarry, etc., were decent fighters.
The 80's was great for welterweights and middleweights ... Hagler, Leonard, Hearns, Duran ... wow. Most incredible knockout I ever saw was when Hearns took out Duran with a right hand that would have killed a mere mortal. Duran fought until age 51, and only lost inside the distance three time - the "no mas" fight, stopped on his feet by William Joppy at age 47 ... and this:
View: https://youtu.be/q2ukZxq8j0Q?t=448