Frazier overall... During his peak run, Fraizer cleaned out the 60s with Machen, Boneneva, Chuvalo, Quarry, Ellis, and Ali. And Mathis was a fine win over a fellow rising contender. Foreman beat Frazier...but otherwise really doesn't have anything on him other than a miracle 2nd title reign.
Foreman, but I wouldn't say easily. Ellis, Quarry, and a little guy by the name of Muhammad Ali help a bit.
Between Quarry and Ellis.. you had two guys coming off wins over top 5 guys like Leotis Martin, Patterson, and Spencer. By taking them two out and than Ali in additon to Mathis, Bonavena, and Chuvalo, Frazier completed one of the more decisive clean ups in history. A terribly underrated run. Even Frazier's second win over Quarry is a huge deal as Quarry had just beat Lyle and Shavers and was pushing for a shot at Foreman.