"baykua"'s a wuss

I find that they both are really strong but I think Kenpachi is a tad stronger then Byakuya.

I CHOSE KENAPCHI. hes stronger... but byakuya is more mature... i'm stuck

Terrible spelling of 'Byakuya's' name there. They would be evenly matched, because they are both incredibly powerful in their own way. Kenpachi excels at swordsmanship, body strength, sheer willpower and huge reiatsu, whereas Byakuya has the advantage of having a 'releasable' Zanpakuto, which has long-range, plus he is calm in battle and also excels at battle tactics. Byakuya, in some ways, is as formidable as Shunsui, who is, no doubt, easily the most capable Captain, besides Unohana.

Even so, I'd say that Kenpachi would probably end up defeating Byakuya... He's just a machine and a boss!