How strong actually is cfyow Kenpachi?

For this post, let's assume cfyow is canon. Like, we know from cfyow that beside him, only ichigo, aizen, and potentially Ginjo, prep urahara and prep mayuri can beat hikone. First thing first, that arguably put prep time mayuri above bankai byakuya and shunsui (let's not say adult toshiro since that statement might have been made while including the form's limitations) which is... interesting. But, it's mayuri and urahara after all, if they carefully analyse all of shunsui and byakuya's abilities and come up with counter, it's doable, so let's admit.

But that begs the question: since base kenny was outpowering hikone, does that mean base kenny > shunsui and byakuya? Then that begs the question, how strong he is in bankai and shikai?

Gimme your opinions guys