Having played both i am more a fan of the ufc game as i think its more for the purists but the ea game is pretty good too,its a personal choice they are both good games so u cant make a wrong decision really!!
I am an avid watcher of the UFC and chat regularly with a friend that plays both. He recommended that I play the UFC game over EA's MMA if I wanted a more "authentic" experience. The EA MMA version is more arcade style in play, less controls to master and quicker to just pick up and play. It depends how patient you are.