u guys are missing my point tho. in a REAL street fight if your say 5'10" 175lbs and your opponent is 6'5" 240lbs.
If that's the case, it may not matter which art you know. you would have to be pretty effective at it to beat someone that much bigger who's intent is to break you in half.
however, a fight is going to go through different ranges. if it starts further out, i.e. kicking range, then having some good kicks would be your best first line of defense. if he gets past that, I would want boxing. if he got past that range though neither is going to matter as you are probably going to the ground.
that's based on going against someone so much bigger.