I say Mei. She can use Hidden Mist Technique and Mix her boil release with it meaning if Kakashi could be melted.
They both have Earth Release and she can layer the ground with Lava to stop any sneak attacks. She can use katon
and the both can use suiton, her suiton seems much stronger.
And he can use raiton.
I give this to Mei. Her skill with elements has seen more impressive particularly her skill with Water dragon jutsu is far superior than his.
Her hidden mist will only help Kakashi
She wouldnt where he is, while he could use his sharingan or sense of smell to find her
Mei cant beat Kakashi
how will he summon dogs when being melted by acid vapour?Or uses tracking fang to hold after earth/water/lightning clones are used as decoys/ tandems then raikiri
why would a kage use hidden mist if she is unable to fight within it? she obviously knows silent killingShe wouldnt where he is, while he could use his sharingan or sense of smell to find her