Let's do a summary.
Freddy: He travels in dreams and gut the shit out of someone inside out. In combat, he's weak as shit and Jason mauled the fuck out of him, but he never dies. He's also pretty fucking smart.
Jason: Let's do Jason from the new movie. Jason is a god damn hulk in this movie and can easily decapitate anything. Now let's put that with the Jason goes to hell thing. Where he get blown up or shit like that. He turned out fine. He's supposedly really dumb or retarded.
Ash: He has a goddamn chainsaw in his hand. Instead of snotty teenagers, he's taken down some pretty hardcore demons and dealt with his alter-self in army of darkness. In the first F V J V A, he uses the Necronomicon to send Freddy in a state of unknown time and space. Then he also sends Jason to the bottom of Crystal Lake with the book.
So Ash would win due to brains and strength.