Jet Li is better because he is faster and stronger and he was five times a wushu champion before even become eighteen years old. But after all he is more mentally ready for a fight like that than Bruce, don't get me wrong Bruce is a legend but with the time pass everything that he has done became ten times more valuable to the people so everyone thinks that he is even better than he really was. But Jet Li is more real and better fighter on Wushu than enyone else.
Bruce Lee is trained in multiple different styles and he has mastered majority of them. Jet Li is not like Bruce lee in training or in style! Bruce lee was by far superior in speed and strength alone and Jet Li doesn't gave either of those advantages not even now.
Bruce Lee will beat Jet Li every time. Bruce Lee is the way more superiorly skilled martial artist. If he was still alive, he would kick Jet Li's butt so many times that Li would no longer have a butt when Bruce Lee was done with him. Bruce Lee is the best ever.
In my opinion Jet Li does not have the skill, or the determination to ever be comparable to Bruce Lee. Bruce was a legend in his own right. He was the most skilled martial artist we have ever seen. His work ethic in his training regimen was very strong. All of these things are reasons why Jet Li cannot beat Bruce Lee.