Okay, first off every special forces virtually goes through the same training, that stuff you see on TV is just their qualifications. During Vietnam the Green Berets were the Navy SEALs of their time, movies were being made of them, songs, books etc. While all that was going on the SEALs had just formed in the 60s and no one knew about them then. Now a days they are the Green Berets in Vietnam, movies, books, video games, everything is being made for them. What most of the general public doesn't know about now is MARSOC, under the Marine Corps formed in 2005. They are some tough mofos. I can't really say who the best is though, they are all really the same thing in the end, just different branches and specific missions.