Good god, my local cable provider just got "The Fight Network" holy crap is there some awsome content, just watched Joe v Punk from sometime in '04, amazing match, outclasses ANYTHING ive seen in recent memory YAY ME :)
I would have to say X7, even though it ended on a slight downer. But that was maybe the greatest PPV ever. A close second is the underrated XIV, which I think was the best show from top to bottom, but without a true classic. XX was too long.