A bit biased here but....I'm going with Bret Hart. Sure Angle is an Olympic Gold medalist, but if we are talking about pro wrestling, I have to agree with Sally. Bret was as crafty as they come. He always knew how to win against all odds. When Diesel was too big and strong, Bret played "possum", faked his fatigue and beat Big Daddy Cool with a small package. When Stone Cold proved too rough and rugged, Bret toughed it out and beat him at his own game. He out wrestled Mr. Perfect, he showed he can handle the speed of the 1-2-3 Kid in a classic title match. Basically, in any situation, Bret adapted and prevailed.
Like Mustang Sally said, no one ever saw Gotch, Thez or Rogers or any other wrestler from the Roosevelt Administration era.
I always held Bret to high regard. Outside of Owen Hart (who was more fluid and a graceful high flyer), Bret was who he claimed to be, The Best There Is Was and Ever Will Be...