Well the first fight was hard largely because Fury had allowed himself to balloon up to a ridiculous weight. I think Pre Ruiz, AJ beats Wilder comfortably as he was still way more skill but also had the power that Fury lacks. Usyk wins easy because he has so much ring IQ and skill that Wilder with his novice footwork wouldn't be able to get close to using his only weapon. Current AJ is broken so he probably loses to most serious contenders but it's not really a fair comparison.Well, Wilder did give Fury the 2 toughest fights of his career. The first fight, he actually almost won, and the 3rd fight was a classic war. I don't see either AJ or Usyk doing as well against Fury as Wilder did in fights 1 and 3 of their trilogy.
Compared with the motivation of trying to get his titles back the age and inactivity are trivial. When he lost to Fury, WK was in a rut of perfunctory defenses and Fury won a fight that was boring as hell with a very small number of actual punches thrown.Wlad was a year and a half older, and was inactive for a year and a half.