I went with Bruce, but this was a tough one.
One one hand, I like Bruce more than Jackie and I feel like Bruce is a more iconic figure, and he did more than either of the other two to popularize martial arts (especially in the western world). The dude is a straight legend and has an aura to him that the other guys can't touch. Where he falls down a little though is in the brevity of his career and the fact that today his films undeniably feel quite dated.
Jackie certainly has had a much longer run that Bruce did. This dude starting making movies in the 60s, became a bona fide martial arts star in the 70s, and is still going today. He's the primary popularizer of his trademark comedy kung fu style and set himself apart by being willing to do nearly anything in terms of stunts, just so long as their was a reasonable chance of survival.
However, in terms of simply enjoying his performance style, I prefer Jet over Jackie. Jackie has the better legacy and the more robust career, but while I think Jackie's comedic style can be fun, I prefer Jet's more serious and bad ass approach and I'd probably rather re-watch something like Fist of Legend or Fearless over all of Jackie's films. Also, The One is underrated.
The winner? Bruce Lee. You could make arguments for any of these guys, but he's the guy who paved the way for followers like Jackie and Jet and I can't help but believe that no matter what they accomplish they will always be operating in his shadow.