Braden and it isn’t even REMOTELY close. To suggest anyone else would be intellectually dishonest. He probably wasn’t Cooper but of the named suspects, he IS the only real answer to your question.
As far as being qualified to make the jump, Braden made over 900 free fall jumps with the military, was one of the test jumpers when the Army was inventing HALO jumping, and was chosen by the Army to represent them at International Skydiving competitions, many of which he won.
Braden was also chosen by Project DELTA to teach South Vietnamese Special Forces how to jump into wooded and jungle terrain in 1965.
Evading capture and escaping? The guy did nighttime jumps with 6 man teams (that he led) into Laos, Cambodia, Vietnam, and North Vietnam from early 65 until late 66. He would be evading capture and certain death/torture for weeks at a time. Braden was the first guy to ever successfully plant a wire tap in North Vietnam.
Again, he likely wasn’t Cooper, but he is the answer to your question. Even if Peca was the only quadruple agent of CIA-Mi6-KGB and Mossad in all of history, Braden still has him beat at this sort of thing.