Vega strikes me as a pretty boy fighter that is uber as long as he isnt getting hit...
I believe one solid punch in the mouth would change Vega's entire demeanor from one of concieted arrogance to one of fear and hesitation...
I think Snake Eyes is tough enough to take some punishment from Vega, skilled enough to land that momentum shifting blow, and has enough heart to follow through on his advantage (while sustaining even more punishment) and melt Vega like a snow cone on a hot side walk...
Snake Eyes for the win...