"Best" is highly subjective when you're talking about personal responses to art. And before anybody flames me, yes, movies are art. Even action movies. What's best for you isn't best for everybody.
For me, it's "Rush Hour" and "Rush Hour 2," because in addition to being irrepressibly charming, Jackie Chan is an absolute blast to watch in fight scenes, and Chris Tucker, especially in the second movie, is no slouch himself. That said, in my list of gotta-have action movies, "Die Hard" is right up there.