Ronda in an all out brawl, but Floyd if its just boxing. As far as I've noticed everytime I watched boxing, they always tie up. If Floyd tied up with Ronda, she would put him on his ass. Then its over in 10 seconds.
My guess is Floyd mainly because he's a lot stronger than her (I think). I know Ronda trains for more of an overall fight potential but I don't know. She would have to get him to the ground to have a chance but even if she did, he's a lot stronger than her.