Why is OSX better than Windows?

I've never owned a Mac OS device. I've been using windows since I was 6 and never had a reason to use something else.

I like my Vaio Z, but when I get a new computer for college next year, I don't know if I should stay with Windows.

I love the way the macbook air looks, and of course it has the best battery life and that will only improve with the new intel processors. A black one would really sweeten the deal, but my only thing is the display. My Vaio has a 13 inch 1080p display, and I'm not stepping down from that. I keep seeing rumors that they'll leave it at 1366 or 1440 or whatever it is now, and that would really suck. But that's besides the point.

What would I lose (and gain) the ability to do by switching to Mac OS? I never see that many Windows v Mac arguments, especially compared to iOS v Android arguments. That makes it seem like they're both mostly the same.

What are the reasons you switched (or stayed from the beginning)?