[Brickhaus]

Just the guys I know enough about to rate. The number corresponds to about the percent chance I think they have of winning a title (e.g., a 7 means I think there's a 70% chance he'll win a title), assuming the Klitschkos only have a couple years left:

Robert Helenius - 7 (but has the best chance of being "great")
Kubrat Pulev - 8
Dennis Boytsov - 7
Vyacheslav Glazkov - 7

Deontay Wilder - 4 (but has a higher upside, if everything comes together, than most of the guys on the first list, but also a very great chance of completely flaming out before even becoming a contender)
Tor Hamer - 3
Tyson Fury - 7 (I'm encouraged by his age and how much he's improved from fight to fight)
Dereck Chisora - 4
Tom Dallas -1
David Price - 3

Alexander Dimitrenko - 3
Francesco Pianeta - 3
Timur Ibragimov - 2
Albert Sosnowski - 1
Alexander Ustinov - 2
Oleh Platov -3
Edmund Gerber - 2
Vladimir Virchis - 2 (too far past it)
Yakup Saglam - 1

I know nothing about any of those undefeated fighters.