I had tentatively accepted Windows 10 on a couple of computers at the office...
... until Microsoft decided to push an update to the ui one day which undid ALL of my customized changes, showing me that, despite the ability to change settings, Microsoft doesn't actually care how *I* want my computer to work, and has no hesitation whatsoever to change it around their way...
... and then there's the day I walked into a client's office to fix something that should have taken 30 seconds and had to wait 20 minutes instead for a Windows update...
I have one desktop running Windows XP, a handful running Windows 7. My main PC and my laptop both run Debian (Linux).