Speed counts if you know the right spots to hit. Stamina counts if you're just gonna start flinging punches left and right. If you hit someone in the right spot, it's friggin hell. I honestly dont know how someone can still be conscious after being hit smack dab in the nose. (at least for me) In my childhood, I was walking out of the front doors of my school, I think I was in 3rd grade or something, and slipping on some icy steps outside, almost literally taking a bite out of a metal pipe handrail. that hurt like hell. Recently, someone hid behind a door, and while walking through the door, this guy tried to tackle me, at least wrestle me to the floor, and accidentally flung the heel of his palm right into my nose. I havent seen that many stars since I smacked that handrail in my youth.
So, I would think that speed, with intent to go after someone's known weakness, or a generalized weak spot like a kidney shot, would result in the last man standing.