Kabuto wins both scenarios with low difficulty.
-Kamui isn't happening as Kabuto is a sensor and has full intel. So he will know Kakashi is using Kamui once he feels him
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. And he'll be able to use
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that blocks LoS. Rendering Kamui useless. Then Kabuto can go underground, re emerge some distance behind Kakashi and fire of Hakugeki and finish up with a chakra scalpel.
-Kamui isn't being used off the getgo when Kakashi has zero intel on Kabuto, but most of Kabuto's moves can end Kakashi if he isn't warped away immediately. Result? Kakashi gets raped.