What is the most diverse and intuitive Special Operations division of any military structure, and what course?

I am looking into the option of joining the military for my future, and if I did this, I would want to be the best I can be, and achieve as much as I can possibly achieve. If I were to join any branch of the military, I would want to be part of it's Elite, and I would like some advice from you on how to achieve this. Any information you can give would be of great help, especially if you are or are affiliated with a current or past Operative of any branch. I would like to know: What the requirements are, what branch and programs will offer me the most out of my experience, what I should do to prepare in anticipation for this, how I should make myself what they are looking for, and the traits of the job i.e. what they will expect out of me, and what I should learn to get these traits.