Rumble in the bronx is a good movie. It's one of the ones I've seen the most times.
I really like both drunken boxing movies(though unfortunately, the latter was only ever released in europe on VHS so I'll have to import to get the dvd, which means I have to get a region free dvd player >_>) as well as project A (the stunt where he fell of the clock tower on his neck ! .. and then, because he didn't like the take, did it two more times.. Wow - It looked like he was about to break it !. Just to mention another crasy stunt he's pulled) and Wheels on Meals and any other movie where he plays together with Sammo Hung and Yuen Biao (that I can think of).. I also find some of his new movies really good, but mostly his chinese work, since he has a tendency of movies with more dept when he makes them in cantonese. Such as Shinjuku incident and the myth. - I do however like forbidden kingdom, even If I did think it could have used a bit more character development to reach "epic" status :P.. The fight between jackie and jet alone makes the movie worth watching.
Who am I is also one of my favorites :P .. As you might be able to tell, I like a lot of his movies. He has done some movies that I didn't think were that good though, like rush hour 2, and the medallion.
@NightDragon83. You should try to watch some of his chinese work, atleast some of his later. It shows that he is actually a very capable actor in other genres than comedy. And some of the movies are really interesting. For instance, In the myth, he plays a general in the past while playing an adventurer in the present, looking for the treasure that relates to the general he plays in the past. And the movie keeps swtiching between the times... Anyways, the real reason I replied.. "Killer Klowns from Outer Space" <- The name alone means I'll have to track it down and watch it :P what the fuck !.. I'll assume it's as bad as teenagers from outer space or starcrash.