DR
Zaraki vs Byakuya
Now this is a real fight. They are both top class Soul Reapers. Either way regardless of who wins these 2 are definately the top 2 strongest Soul Reapers. I think that Zaraki would win in a very close fight. While Byakuya does have bankai while Zaraki doesn’t. Zaraki could still take him because of his sheer strength and spiritual pressure. It was been known to outclass even other Captains. He even took on 2 teaming up. But Byakuya also has skillz. But now Byakuya has surpassed Zaraki. Byakuya wins.
DReager1.com 
It would only be a close battle because Kenpachi likes holding back. If he started out at full power and using kendo, that battle would be over in the blink of an eye.
I don’t know, these guys are both so strong they can’t be hurt, in the end no one would ever lose