What's the hammer in this case? Purely combative arts like modern military systems. Things like Krav Maga, Systema, or MCMAP. Those arts are designed for a single purpose, eliminate an enemy combatant as efficiently as possible. That's why they're trained in by the Israeli Defense Forces, Spetsnaz and Marine Corps, respectively. Both MMA and traditional martial arts have their places, but why argue over what is best for self-defense without including arts that were specifically designed for modern self-defense?
Invariably, it comes down to how effective the individual combatant has made himself against the strategies and techniques used by the opponent. If you behave in a manner that prevents others from wanting to hit you, it's a win in my book.