can use 8 swords at one time perfectly and was able to stomp Sasuke's sharingan that couldn't keep up with his moves. Not only that but he now has Samehada.
Can Mifune do any of that? or anyone in the manga in that case?
I wouldn't pick ether of the too. Mifune needs to use more than samurai sword, an have we ever seen Bee do anything more than carry samehada on his back? Show me scans of him using it and we'll talk.