Goldberg
I often find myself pondering this. Let's just step back and consider his credentials:
Skyrocketed to stardom and led a then white hot WCW to the top for a year and a half straight. There was actually talks of WWF folding at the time of WCW's dominance.
Was the main star of WCW. Held a record of 173 victories to start his career, which was far more than the nearest competitor (come to think of it, who was the previous record holder?).
Took out Hulk Hogan for the belt in Atlanta Georgia before 40,000+ fans!
Came to WWE on his time. Didn't bend a bit, and took out WWE's top star of the last 5 years and the next 15-20, HHH. Took him out, took him out good, and got out when he felt like it.
Continues to be a Superstar, appearing on a variety of tv shows and movies. He's not set to come out in an athlete reality show, on which Jerry Rice and Karl Malone have already been confirmed. That's some pretty elite company he's joining with those two.
Admin it he was the strongest wrestler.