I'm taking JDS in this one.
I know he got his ass handed to him last time, but let us not forget that he got rocked bad ealry on in the fight. If he didn't eat that punch, things might have gone much, much differently.
People want to say JDS got lucky by KO'ing Cain early in the first fight and that the 2nd fight was the "real" fight or whatever, but I would argue that the only thing proven was that either JDS hits harder than Cain or Cain has a weaker chin than JDS, because JDS KO'd Cain with one punch, while Cain couldn't do it to JDS in 5 rounds.