Bivol, he actually has hard hooks and can counter with power a lot more. Not just the slappy right hook that Usyk has and the winged left hand
Only one of them has beaten the p4p top dog. And that man...is Usyk. Who beat Chisora...who is p4p top dog of my heart.
Bivol is pretty good at what he does. He isn't a complex boxer by any means, but like Mikey Garcia, he excels at the fundamentals. I feel as though Usyk is a much more complete, and deep boxer.
No one is better than Usyk in terms of boxing brain/skill. Usyk's only let down would be his physical attributes aren't anything special. So maybe one day someone will be too much for him physically.
Chisora made a similar mistake to the one Hagler made against Leonard. Had he fought the whole fight southpaw like the 7.2 seconds where he out jabbed Usyk he would have won.