No one. UFC is where REAL fighting takes place. Outside of a few exceptions NO ONE can just jump over and make a "transition" from a NON COMBAT sports to combat sports. WWE is scripted fake fighting vs. the UFC where most trained their entire lifetimes just to earn black belts in different techniques.
I could see Cesaro doing pretty well if he took the time to train. You can't discount his strength even if he would be a little behind the curve with technique. Swagger might be decent as well given his amateur wrestling background.