I can't be bothered thinking of an order, but just pick 5 from: Roberto Duran Ray Leonard Pernell Whitaker Salvador Sanchez Wilfredo Gomez Bernard Hopkins Roy Jones Jr. Julio Cesar Chavez Alexis Arguello Marvin Hagler It depends on if you're only counting accomplishments post-1980. Guys like Arguello, Gomez, Duran etc. all did a lot of good work in the 70s and 80s.
He is by far and away the greatest cruiserweight ever IMO, and has a strong resume. I thought more people would have put him forward. I think he would be my number 6.