Before Windows 3.1, most computers with a GUI that I used were running CDE. Mostly Sun workstations, but also a few Alpha and AIX boxes. And one SGI running IRIX. My first home computer with a GUI was Slackware Linux with FVWM. Unless you count the GEM desktop on a C64.
Windows WFW 3.11 - was pretty ok. First version of Windows I used daily. There were lots of useful, or perhaps too many necessary, hacks in the early days of the internet.
Windows 95 was, in my opinion, pretty cool, and obviously was a real game-changer in terms of UI.
Windows ME was a horrible aberration. Garbage. I only experienced it on friends-and-family computers I would get summoned to "repair". Usually pre-installed by HP on the horrible boxes they were selling at the time. Note: HP did, in my mind, redeem themselves years later and resume making real computers.
I worked with Windows NT 3.51 and 4 a bit at various workplaces, but for server OS, almost everything was already Linux even at that time (1999-2002 time frame).
Windows 2000 was fantastic. Rock-solid. I never ran XP at home, just stuck with 2000 because there was no compelling reason to "upgrade". For a home and small business OS, I really think MS nailed it with 2000.
Windows Vista took more of a beating than it deserved. I ran it at home for a couple of years and had no real complaints other than the UI was pretty ugly a lot of the time.
Windows 7 was and still is fantastic. I love it. My computer does exactly everything I need it to do, and is crazy stable. Less crashes than even with 2000, which almost never crashed ever, anyway. I really do love Windows 7. Currently in my house we have Macs running Mavericks, my Win 7 box, and I boot to Manjaro Linux on occasion to get some work done that I just don't find practical under Windows because I never learned Powershell.
I tried Windows 8.0 for a while and was absolutely shocked at what a disaster it was. Just unbelievable. I never tried 8.1, which I understand fixed things considerably, but as I said, I love Win 7 and like with the 2000 -> XP shift, see no compelling reason to upgrade.
I am honestly intrigued by Windows 10 and will give it a spin when the preview is actually available, so perhaps even later today.
(Can't believe I am bothering to post this)