To me, MacOS just seems like the best desktop UI and UX out there. I'm talking about stuff like font rendering, gestures, multiple desktops, etc. All of these things on the Mac have clearly had a huge amount of thought put into them. And since these things mediate your entire interaction with the computer, it's a big factor for me.

Windows seems to be a combination of 90's era throwbacks and 2edgy4you Metro design. If they've managed to improve this stuff recently I would be interested in switching, since there's a huge tax on hardware specs with Apple computers.