I would say that the prime of Hopkins extended from 1997-2001. Although I think Jones beats prime Hopkins, he certainly hadn't developed into the same fighter when he faced Jones as he did throughout the middle of his championship reign.
Pernell Whitaker Roy Jones Jr. Aaron Pryor Carlos Monzon Salvador Sanchez Marvin Hagler Khaosai Galaxy Joe Calzaghe Ricardo Lopez Jung Koo Chang Ike Ibeabuchi I'm also hesitant to say Juan Manuel Marquez, Naseem Hamed, Orlando Canizales, and Gerald McClellan
Joe himself made it clear he considered Max Baer to be his all time peak performance. Schmeling I came nine months later, so Louis clearly has to be eliminated from consideration.