I find it to be a pointless argument to reduce to two halfs. Of course there's going to be more artistic merit and flourish in World cinema as opposed to Western cinema, considering how large the world is and how many varying countries with different beliefs, cultures, languages and conventions are abound. To classify so many nations under one banner and then a few under another is a bit ridiculous, I recently studied some Eastern European cinema and by god there was an awful lot of diversity and styles on offer, and that was just one small part of a single continent. That also generally only the critically lauded films getting releases over here also blurs the truth that every country makes shit films.
Then there's the issue of Western cinema that doesn't get wide distribution, of which there are plenty of hidden gems and plenty of utter tripe. Yeah, it's a bit of a silly argument.