Work: Windows 7 because I have to use it and because work supplies a worldwide, 24/7/365 IT dept to patch and maintain it.
Home: Xubuntu and Mac. Got no time anymore for that Windoze crap.
I am using 8.1 on an old Compaq (Amd 64-x2 3gig ram) and have Classic Shell installed feels less jarring than even 8.1 “start” button.
when 10 is released I will get the free upgrade and give it a whirl.