Best fighting style for real-life situations

[r3vbr]

say you are in a war and really wanna kill or disabilitate someone 1vs1, both unarmed, wich style is the best to know?

I've seen a LOT of people say that Brasilian Jiu Jitsu is best because it wins alot at UFC and all, also some people say Muay thai is good, but It's hard to believe all those fancy bruce-lee kung fu/shaolin styles are not at all effective. and If jiujitsu is best is that what they teach in the military?