The answers to these questions are interesting and can contain a multitude of responses depending on how the person answering defines bravery.
Which type is the bravest? Why?
An interesting question.
My Dad is an ESTP retired Army Colonel. I have seen him strike fear in the hearts of men my whole life, whether it was a direct report of his, a room full of men whom he caught screwing something up, or some person that earned his contempt in our many encounters in the civilian world.
These things (his manner, disposition, authoritarian tone and body language) I learned from him as I was with him alot growing up and observed him in countless conflicts of all varieties.
I am ESTP too, and I agree with Sytpg, that fearlessness is part of the type, for sure. My father and I are both fearless and have been since exiting the womb.
Regarding bravery, I think that bravery can be transmitted genetically as can type, but I also think that bravery is learned. My Dad taught me a few things from an early age, which I consider foundations of bravery:
(1) Emmanuel Kant's categorical imperative of duty: "Do the right thing because it is the right thing to do."; [I chew people out on principle all the time! It's horrible!] and
(2) Hegel's "Might is right.", [Hence me being a bodybuilder + wrestling/karate as a kid] and
(3) As stated in the Bible, there is only one way to deal with conflict: "Head on."
The lessons above are those I called on when situations in my own life called for me to be brave. I got into alot of fights in elementary school, not for being a bully, I was notorious for taking out bullies. If I saw some kid bullying another I'd walk right up to him, tell him to stop, and if he mouthed off or did not relent I took him down, that simple. Then off to the office I'd go, Dad gets called, comes in to the office in full uniform, listens to the principal's report, then asks me if that is what happened, and then told the principal "If your faculty were doing their jobs policing the playground and keeping it safe, my son wouldn't have to do it for them."
Having the mentality I do is no doubt nature + nurture. I'm brave and fearless, but not reckless...any more. Even us ESTPs chill out a bit with age...a little
Other types that seem to have great potential for being brave, definitely ENTJ. My buddy Andrew is a "Field Marshall" and he is one brave S.O.B.
"How dreadful!" cried Lord Henry. "I can stand brute force, but brute reason is quite unbearable. There is something unfair about its use. It is hitting below the intellect." ~ Oscar Wilde - The picture of Dorian Gray
what? i can see an esfj being the baddest bitch on the block if it means protecting his/her community or family. seeking out new experiences or diving into good-potential filled unknowns does not entirely comprise "bravery." fearlessness is influenced by context. i can see an opportunist nt or sp balking in certain situations that nf's or sj's would defend honorably. f's might be more emotionally brave and t's might exhibit more courage in independent action. and i see n's more defying social norms, especially nt's - but to them, it's not so much an issue of bravery (since they don't place that much value on social norms in the first place) but of ingenuity, efficiency, reason, or creativity: new ideas, concepts, applicable theories, etc. all that being said, ne leads me into dangerous and exciting worlds!
ETPs are definitely the bravest, but ENTP makes the better leader because of their intuition. (By leader I'm referring to an idealistically based leadership, so this fact solely depends on the concept)