Acting- Jackie Chan. He can cover a wide range of emotions.....
That's not to say that Jet Li isn't a good actor. Both are good, but it seems like Chan is the more well-rounded actor(in terms of the movies he's in) where as Jet Li is primarily in drama/action movies.
Fighting- Both are good, but I'd give the slight edge to Jackie Chan.
Charisma- Jackie Chan. More people know about him, he's known in & out of the martial arts genre, and he's the 2nd highest paid actor in the world(The highest, of course, is Dwayne "The Rock" Johnson).
Performance- I'd say it's equal.
Legend- Both are legendary and will leave legacies in martial arts & movies that will be remembered for years to come :)