Sorry but you are underestimating Zoro… I like kenpachi a lot… I think if he had Haki he would be superior to Zoro and Zoro would need to fight an uphill battle but
first endurance while kenpachi has insane endurance, Zoro has Insanely Op endurance… what I mean by that is that the more he takes damage the stronger he becomes, literally couldn’t even scratch someone no matter how many times he attacked to then being so damaged to the point of being in near death state and instead was able to one shot him as it was nothing. It’s stated that Zoro lost 3 liters of blood while
fighting mihawk and later 5 Liters on arlong park, that’s literally losing every single blood from his body and still being alive… I mean Zoro is fighting Death himself with his willpower and keeps winning…
Link and
Link
I never saw kenpachi ever having feats like that.
Durability - Zoro has advantage as his stat amps increase his Dura
Speed - Zoro is easily above with speed, techniques that speed amps to the point of nearly getting blitzed to later being full blitz
Skill - Zoro has takes that easily… I mean just read the profile of Zoro’s intelligence section
Range - Zoro takes that as well not only that but they are wide aoe air slashes which he spams and uses them effectively close range, mid range and long range
Sensing - I mean Zoro absolutely destroyed in this… using pre timeskip Zoro sensing would be fair.
AP - Zoro one shots island lvl characters with Haki… Damage boost… Zoro one shots people that before with his regular slashes couldn’t even scratch the person no matter how many times he attack but after using Damage boost, one shotted him. I see Zoro having the ap advantage plus can amp more with Asura and gorilla techniques which is kinda overkill
overall I see Zoro winning this low diff (profile) or high diff (My headcanon of Kenpachi’s capabilities)