Byakuya actually has the best feat of raw destructive power here via smashing the head of the strongest version of Gerard any of them were able to damage over the course of the fight. However he simply has no answer to Hitsugaya straight up freezing his petal blades and rendering him moot, but I would definitely put him above Kenpachi in general.
Hitsugaya of course casually cut Hoffnung (Gerard's sword) in half where Shikai Kenpachi could barely chip it and was powerful enough that a Gerard who had been cut in half (and therefore powered-up further) by Bankai Kenpachi, had to struggle to resist the ice coming from his body passively.
In short the ranking is:
1) Toshiro Hitsugaya
2) Byakuya Kuchiki
3) Kenpachi Zaraki