Linux; not all non-Macs runs Windows.
But you didn’t list that, so given the choice between crap and shit, I’ll take crap. In this case, that means Windows.
While @zenvelo says Macs are “easy, reliable, and versatile”, I can shoot down all three of those. Ease started to fade when Windows came out, and pretty much went away with Win7. And Linux has become even simpler than either; simple enough that my 13-year-old cousin figured it out in 2–3 minutes. In fact, for many of the sorts of things I do, it’s actually harder, if not outright impossible on Mac because Apple likes to lock their stuff down. Reliable…. not so much. Then again, that would imply that Windows is more unreliable than it actually is. That’s a draw. Linux is reliable enough to be used in mission-critical things, so it untouchable in this area.
And versatile? Complete, total, and utter bullshit. I think 95% of the stuff I run would only run on a Mac if you used Boot Camp or a VM to boot the Windows, and it would run poorly since the GPUs in Macs tend to be underpowered and non-upgradeable. Sure, the new ones are better, but graphically, most iMacs would still be unable to match what a PC could do at ⅓ the price. Linux can run some OS X stuff thanks to the similarities between Linux and FreeBSD which OS X is based on. And WINE has come a long way, so it run a lot of Windows things already.
The only things Macs have going for them are looks, customer support, and resale value. I do all my own work, so tech support is useless. I run my systems into the ground, so resale value means nothing. And if I wanted pretty, I’d be into case mods. So the three things they can beat a PC on are all things I care nothing about. Oh, and Apple logos give street cred to people worried about being “cool” or “in”.
Don’t take that to mean I actually like Windows though. It has a lot of ass-backwards things about it, and more than a few problems. However, it can run just about anything I want to run, which right there makes it 100 times better than OS X. And I can get hardware that runs that stuff better than a Mac could run it for far cheaper. Since Apple is actually not tops in reliability, cost and ease of repair mean a lot. That comes into play every couple of years when I need an upgrade too. Mac users would replace their entire system for over ten times what I paid to just get a new mob/CPU/RAM to upgrade my 2009 budget box to a 2015 mid-range PC.
But I have to give Linux props. The UI can be altered to look like OS X, Win7, Win95, Win3.11, or have it’s own unique desktops like MATE or Cinnamon. The same things that make Macs allegedly virus-proof are just as true of Linux since both are UNIX-derivatives. It’s security and performance are good enough for most servers, banks, governments, and the DoD.
@jaytkay I have a few non-techhead friends that couldn’t handle the teeny-tiny iPhones. While the 6/6s is okay, I would not recommend the earlier (smaller) ones for anyone much over 5’5”; only the petite and the underage have hands small enough to use them comfortably. And if my non-geek wife found Android intuitive while iOS was jsut unusable, that right there should just end the debate.