Not really sure how to compare the two!

I don't honestly know which has more fans, but honestly, having more fans doesn't necessarily make you better. I'm yet to hear an intelligent debate that compares Mozart to Skrillex; the attachment you posted looks like text-speak spam rather than a proper argument. Does that person even know how to spell the word "you"?

But like I said, as it'd be difficult to compare them (because they're so different and likely appeal to different audiences) maybe that's because most people don't know where to start!

Of course, that doesn't mean a person can't be familiar with both and like one over the other. Nor does it mean that a person can't love both artists. We all have our own tastes and preferences (heck, my top three music genres are jazz, metal, and classical).