Top 20 not in any order.

Pernell Whitaker
Julio Cesar Chavez
Larry Holmes
Wilfredo Gomez
Salvador Sanchez
Sugar Ray Leonard
Roy Jones Jr
Marvin Hagler
Roberto Duran
Thomas Hearns
Ricardo Lopez
Felix Trinidad
Oscar De La Hoya
Azumah Nelson
Bernard Hopkins
James Toney
Lennox Lewis
Evander Holyfield
Floyd Mayweather Jr
Erik Morales

These names come to me first.