Tobirama wins mid-difference. Only not long ago, Kakashi's Kamui was shown in its actual laughable colours. He tried to Kamui the Mezo's head. It was there for a few seconds with the Warp Point on it, and yet he missed and got its arm instead. Then when he used it on Kamui, the bloody moron was walking with the warp point plastered on his ass. The large lag in the actual warping allowed Obito to cancel it. Thinking that Kakashi gets any fast opponent with FTG is fanfiction.
Tobirama has shown to make one extra clone during battles and so has Kakashi. But Tobirama outlasts the latter because of his large chakra reserves. Kakashi is not as fast as Tobirama, so in CQC battle, Tobirama has the advantage, who knows Thunder God Slash as well. If Kakashi gets marked, which he will be given that he isn't all that fast, it's over for him anyway.
Tobirama has shown to make one extra clone during battles and so has Kakashi. But Tobirama outlasts the latter because of his large chakra reserves. Kakashi is not as fast as Tobirama, so in CQC battle, Tobirama has the advantage, who knows Thunder God Slash as well. If Kakashi gets marked, which he will be given that he isn't all that fast, it's over for him anyway.