I think a lot of people are underestimating Orochimaru's abilities—he is no pushover when he's at full health. If you recall, during the Four-Tails fight, Orochimaru was BISECTED and lived; and he wasn't even at full strength!
A lot of arguments I see are things like "Well Oro can't counter [insert jutsu/Mangekyo technique]"
If you remember, one of Orochimaru's ambitions was to learn as many jutsu as he could; and he learned a LOT of them (as by his own boasting and as seen in combat). On top of that, Orochimaru has a sly nature of avoiding techniques anyway; chances are, he's got SOMETHING to counter techniques Sasuke can throw at him.
Even if Orochimaru DIDN'T have a way to counter things like the MS techniques or Blaze Release, a lot of arguments act like Sasuke can just spam them; well, he can't. Sasuke gets fatigued from overuse. In any case, lots of people seem to be making the assumption that as soon as Sasuke hits Orochimaru once, Orochimaru is automatically dead. When did Sasuke suddenly become able to one-shot people with ANY jutsu?
Focusing on the MS techniques, Orochimaru desperately wanted the Sharingan—I think it's easily assumable that he knew of the Mangekyo and its abilities! He had a lot of resources at his disposal, and I think it's been shown over time that he used them wisely.
In short, Orochimaru takes this victory.
Just my thoughts. =]