Sultan's quick and decent, but I'm not high on him. I feel he wouldn't still be a belt-holder beyond 2 defense.
Ibragimov is a hard hitting south paw with good speed. What gets lost when talking about him is he can box. Ibragimov might not be the best heavyweight out there, but he is a sure fire top 5 guy right now who can win by slugging, or boxing.
I'm a bit disappointed with Ibragimov because I know he can do more and better than he had shown lately but as you say, it's hard to argue when he is still winning his fights. Because his "asthma" is exaggerated bull****. If it were as bad as he claims he wouldn't be able to compete on a professional level at all. The real reason his stamina is as nonexistant as it is, is because he has become an insanely huge, roided up muscle freak. It's the same as with Cyclists, like 50% of the Tour de France riders claim to have asthma because then they are allowed to take medication that is on the doping list.
I don't like him very much but he is available as an undefeated opponent for the real champ Wlad as King is controlling Peter and Chagaev is idle (may be pondering a move towards King?). He will get by Thompson, barely and get KTFOd by Wlad.