The big difference between Chief falling from space and Iron Man falling from space is that the portal to space where the Chitari were was inside the Earth's atmosphere. Chief went from space to a planet surface, and experienced atmospheric re-entry. Tony didn't have to deal with the heat and such, just a clean enter and exit through a portal.
I give that one to Chief.
But still, Thor. --- "Gary was here. Ash is a loser!" = Greatest Tramp Stamp Ever
Well it seems we would have to agree to disagree about it :)
Having never read the Halo books or Iron Man comics, I'd say iron man only because while he seems to be listing more and more reason why Iron Man would win, you keep reaponding with "lalala I'm not listening." --- "The great thing about the internet is you can make up a quote and claim somebody famous said it." ---George Washington.
If going by the books' description of Master Chief and not the gameplay, then I would think Master Chief would win, since he can move extremely fast, has extreme strength, and has training in most weapon tech. --- "EVENT ENDED!" ---