Yep, syncromesh's chronology of the Windows platform is spot-on in my experience. I have thought about this a lot over the years and I think after each success, Microsoft, for whatever reason, decides to go off on a different trajectory (I think Win Me: dead-end, and Vista: dead-end). I haven't seen Windows 10, and I have been grudgingly getting along with Win 8.1 for a little over a year now. I'm thinking, and hoping, that as far as Win 8.x is concerned, it's another dead-end, however, there are some redeeming qualities about it that I hope they retain. First and foremost is backward compatibility. It seldom worked for me in XP with certain software, worked a little better in 7, and works fantastic in Win 8. Of course, there are some that won't run, and that's to be expected, but by far Win 8.1 runs more of my older software than any of the previous 3 (I'm leaving Vista out of this, My Vista machine is connected to my piano and that's all I use it for, but it sucked completely as far as that goes!.) Another thing I hope they keep is the fast boot ability. Enough said about that topic. There are others, but when I look back even further, DOS 6 was my last favorite before Win 95, but Win 95 was a treat compared to any Windows before it. I think Win 3.x was actually my first experience with "Windows", and at the time it seemed to me that someone had simply put a video game interface on the OS (the "GUI"). It turned out I was more or less correct. I saw the potential for it, though, it was simply rough in my opinion and memory of course wasn't cheap at that time. XP, though, was, is, and will always be my favorite OS. It brought one thing to Windows that hadn't been done before: STABILITY! (relatively speaking, of course!) They all (post-XP) recover from crashes pretty well, now, but that was the first I'd seen of it. XP will be my favorite at least until I see and work with 10. Perhaps (and I hope) the pattern of win/lose/win/lose is simply a learning process for MS.
EDIT: One OS that wasn't mentioned was Win 2k: also an excellent OS, and I've four very old tablets that run it, but 2k was found more (in my experience) on enterprise machines than elsewhere.
MAME Cab PC: i7 4770@3.4Ghz (passmark 9945), 12GB RAM, Win 8.1/64, GeForce GTX645 (passmark 1898); Shiny new laptop: i7 4800MQ@2.7Ghz (passmark 8586), 16GB RAM, Win 8.1/64, GeForce GTX870M (passmark 3598); Old laptop: i5@2.3Ghz, 8GB RAM, Win 7/64, Intel 3000 graphics