Holy crap, this thread is almost a year old and the debate still wages on.
Granted I only looked through 14 pages, however.
While I'm inclined to say Halo, I won't elaborate because I'm pretty sure all points have been stressed by now, however...
If, say, an MJOLNIR user does defeat an N2 user, you have to account for SECOND. Even when the user is dead, SECOND is some sort of super A.I that can do things by itself, though rarely. The MJOLNIR user could kill the N2 user most likely, but what about trying to destroy the A.I?
Why would the Spartans invade earth when they were created to protect it from rebels and later covenant and they don't drown if the water is taller than them its for the game so you don't get people hiding in the water in the books the one guys radar sensor was off bc it had salt on it from the under water mission he was on recently.