Bruce Lee was a black belt of wing chun, then went on to learn aspects of lots of other MA's. Then developed his own called Jeet Kun Do which was effectively the first MMA. He taught many many people including Chuck Norris.
He was an insanely formidable fighter and was in many street fights in his time. He was at the peak of physical pefection(in terms of speed and power). He could do a 2 finger press up(one hand). Getting kicked was like "being hit by a car".
Jackie Chan and Jet Li are both performers. Effectively glorified dancers. Not to say I dont like them, really like all their films. But in terms of combat they are'nt nearly as experienced as Bruce.