Happy Together is definitely my favorite WKW film.  Although I saw Chungking Express first and loved it, Happy Together is the film that speaks to me the most.  Chungking is fun, but very light compared to his serious films like Ashes of Time, Fallen Angels, and HT.  What is it about HT that I love so much?  The acting, the cinematography, but I think most importantly the tone.  The film is such a thick emotional experience that I can only watch it once or twice a year - no more.  Few other films come close to this level of respect in my mind.