Who's arguing? Every emulator has its best-comings. 1964, for example, has integrated netplay, and Mupen has one of the easiest user-interfaces I have ever seen in an emulator. But, out of statistics I have seen myself, P64 has the best compatability in terms of ability to play, and (usualy) speed.
Of course, if you prefer Mupen, 1964, ULE, Corn, or whatever, it's your opinion, don't let me get in the way with it. ^.^