For consideration perhaps? Peter Jackson Larry Gains Jack Sharkey Max Schmeling Archie Moore Roland LaStarza Floyd Patterson Jimmy Ellis Joe Bugner Greg Page Ken Norton Tony Tubbs Tim Witherspoon Riddick Bowe Michael Moorer (some listed have already been cited, no doubt)
Ooof that is a difficult question to answer. Floyd Patterson Ezzard Charles Jersey Joe Walcott Ken Norton Max Schmeling Vitali Klitschko Riddick Bowe Archie Moore Gene Tunney Tim Witherspoon There's ten, not sure of the order.
Doug Jones, Eddie Chambers, Chris Byrd. All of them gave up size and length in their eras, but their boxing skills kept them competitive.
I consider a lot of these guys ATG so I focused on the skilled not top 15 part. Avoided giants and power punchers unless they came from a lower weight class. Peter Jackson Armstrong Frank Childs Philadelphia Jack O Brien Jack Johnson Root Schreck Hart Jack Twin Sullivan Ketchel Jeanette Kaufman Dillon Carpentier Battling Levinsky Weinart Tommy Gibbons Miske Mickey Walker Stribling Jack Sharkey Risko Schmeling Loughran Braddock Tommy Farr Schaaf John Henry Lewis Ettore Jersey Joe Walcott Godoy Mann Conn Pastor Archie Moore Nova Lee Murray Tami Mauriello Bivins Maxim Ezzard Charles Baksi Clarence Henry Baker Patterson Folley Machen Mildenberger Ellis Bonavena Quarry Bugner Jimmy Young Michael Spinks Pinklon Thomas Witherspoon Tucker Buster Douglas Holyfield Moorer Chagaev Eddie Chambers Calvin Brock Ibragimov Skelton Haye Povetkin Tony Thompson Luis Ortiz Usyk Kabayel