Great thread!
It would be totally analogous to ask, "What single weight exercise will give me the best body?"
Answer: none of them.
But mix all free weight exercises (heavy power work, light speed and plyometric work, and middle range repetition to failure work), machines, and body weight/free weight training in a unique package that together addresses your weaknesses and maximizes your strengths, and you have a body well-tuned and trained to meet your demands.
I guess you could call this jeet kune do, but JKD is really a pan-style philosophy rather than a particular style of training. And unfortunately, JKD is more often a marketing term for scams nowadays.
What works best is to train your body and to learn techniques that together enable you to move your body through space so as to increase your chance of survival when facing any situation unarmed. This is probably an impossible task to finish anyway. . . But it's like a chess game. There is no killer move that always wins. It all depends on what is happening, what the evil forces of destruction (i.e. your opponents) are doing, your physical, mental and environmental limitations at that moment, etc. You make the best move you can come up with at the moment in a fluid way.
Practically, the best thing to do is to take a little of this until you're tired of it, then take a little of that, and so on. Synthesize it so it's right for you. Then expose your ongoing work to the laboratory of real combat (MMA and NHB most safely) to test your ideas, discard the losers and keep the winners.