Great thread! tough call but here how I have it:

1- Larry Holmes
2-Lennox Lewis
3- Evander Holyfield
4-Mike Tyson
5-George Foreman
6-Riddick Bowe
7-Wlad Klitschko
8-Michael Moorer
9-Vitali Klitschko
10-Cant think of anyone else worth mention..