Roy Jones Jr vs Michael Moorer. Jones was untouchable at light heavyweight (pre John Ruiz title fight). Michael Moorer won every light heavy match he had AND he won them by KO. Moorer was also no slouch in the speed department at light heavy.
It appears that their prime are only separated by 6-7 years, the fight could of happened. Too bad Moorer never got the publicity buildup he should have and probably never considered for any all time great status as Jones surely has and will continue to get.
My pick, Moorer...