I would have to go with Rua. Rua has the ability to keep the fight standing. Mousasi can hold his own standing, and would probably catch Rua with some big shots. I think Rua breaks him down, busts him up, and wins by spectacular stoppage.
I get the feeling they are pretty much on par with one another. Gegard seems so technically, and tactically sound in the ring.. He has a sort of calm demeanor while he dissects his opponents. The thing about Rua is, he isn't a guy you can really use a methodical style on if he's peak. Rua, has shown he is capable of the same sort of in fight strategies as Gegard.. I really don't see one guy better than the other. They are more similar than they are different.
I would say Mousasi. He's got great boxing, kick boxing and grappling. He is a freestyle ala Fedor and I think he could get better. When Rua is on he is unbelievable. Give him a good gas tank and we are talking about a black belt Muay Thai and black belt BJJ so he is a bad man.
