Well let's see. I'll step through the Windows versions I've used and give my three cents (inflation you know!)
Windows 3.1 (and 3.11 for Workgroups)
I liked it's simplicity and ease of use on top of DOS. I could always shell out for games and utilities. But it was sure lacking in terms of stability. Still I miss those days
For what it's worth, I ran Win3x apps under OS/2 2.1 and OS/2 Warp 3 a lot of the time. I stayed with OS/2 right up until August 1996. I really loved OS/2, and I've tried eComstation 2.x recently, but it really leaves a lot to be desired next to new versions of Windows.
Windows 95
You know, as bug ridden as the original Win95 Upgrade release must have been, I had no problems with it. Likely though, that was because I was still mostly running 16-bit apps, thus not really putting the OS through its paces. I used LFNs Now to use long filenames with Office 4.3 and my old 16-bit Windows programs.
I did try the Nashville Beta (Windows 96) and REALLY liked it. It would auto select icons just by hovering the mouse pointer over them, and launch without a click. I did eventually move over to Windows 95 OSR2 B, so I could use FAT32 volumes.
Windows 98
Especially when using audio editing and automation programs, Windows 98 was MUCH more stable than 95, but I soon upgraded to 98 SE, and that was even better. I had my P 200 MMX Classic all decked out to look like Windows 2000 (with icons and Tahoma...lol). Except for a couple attempts at running Windows ME, I ran 98 SE all the way up to 2003.
Windows ME
I don't think it was as all bad as many say it was. I liked the Windows 2000 look, and it had newer features like integrated USB flash drive support. But sometimes the file/open dialog screens wouldn't retain their settings if you changed them. And their were some occasional desktop fonts issues. I think Millennium Edition could be easily tweaked into working as a great OS, but in the end, I found 98 SE to just be more reliable for me.
Windows NT
I liked v3.51 because it was stable and solid, yet it had the Win3x look. But Windows NT 4.0 was a solid performer, and had the same look as Win95. I used the Server build more than the Workstation build, but my only complaint was, there way no way to add USB support (other than for keyboards and mice)
Windows 2000
Up until recently, this was my favourite version of Windows. I felt it was an exceedingly stable yet down-to-business version of Windows, with just enough glitz to make it pleasant to use (fade in menus), but without the bloat that XP had. I ran Windows 2000 on an AMD K62-450 system with 392 MB of RAM and it ran quite well. And it smoked on a Dell Optiplex PIII 866 MHz system with 512 MB of RAM.
Windows XP
In 2007, I bought an HP xw6000 system with a Xeon 2.68 GHZ CPU and 2 GB of RAM. I was all set to install Windows 2000 on it when I booted it up, and found that the preinstalled copy of Windows XP just flew on on it. So I stayed with it. And when I bought my xw8200 Workstation just three years later. I ran XP there too. It smoked with 2 Xeon CPUs even with visual styles applied. I thought I'd be perfectly happy with XP except.... (read the next one)
Windows XP x64 Edition
In November 2011, I decided to experiment with 64-bit XP. It was a natural fit for my xw8200 workstation. All of the hardware drivers (including the integrated u320 SCSI controller) were all included. Installation was a breeze. Sure there were some setup related hiccups, like getting MSE to work on it (I used the x64 build intended for Vista and 7).
But once that was all sorted out, Windows XP 64-bit Edition represented what I considered to be and still recognize as the absolute best computing platform I've ever had. I know I'd be in the minority saying that, only because most systems will not fully support it, since Microsoft looked upon XP x64 as an after thought. But since I had the right machine, it was a beautiful computing experience. Dual Xeons and 7 GB of RAM! Yum!
I ran XP 64-bit until February 2014. I really wanted to run it for longer. It ends up I found a source of updates post April-2014 and an x64 build of Pale Moon that would run on it. That means I could have run XP 64-bit Edition for another year. But a year ago February, those options were available. So I bailed and went to..... (next section please)
Windows Vista
When my boss purchased a new notebook in February 2006 preloaded with Vista, I was excited to try it out. The key word there is "was". Vista's RTM release was so slow and crash-prone. I guess it really didn't help that his notebook was only equipped with 1 GB of RAM (still huge at the time).
But move ahead two service packs later, and now on my much beefier workstation, the x64 build of Vista is quite a solid fast platform. It run pretty much as fast as XP, it's prettier, and is VERY stable. But I only ever recommend using the x64 build, and it seems to work best when used with a source that has SP2 built right in. And use it with at least 6 GB of RAM. I have 7 GB and my setup runs with aplomb.
Windows 7
I dunno, I'm sort of "meh" when it comes to Windows 7. It's certainly QUITE solid and stable, but I'm not big on the iconized thick taskbar (yes I know that can be changed) but I just like Vista better. Plus I hate the ribbon being used on some apps.
Windows 8.1
I would bypass 8, but 8.1 with Update 1 runs quite briskly (better than 7 if you ask me). Plus, install Classic Shell and hide all of the Metro/Modern elements, and you have a somewhat modern looking, better running version of Windows 7.
I plan to upgrade to it when Vista support expires in 2017. As for ribbon apps, I can just take the Paint and WordPad apps from Vista and place them in to the installation, and then I'll use the Windows 8x Ribbon Removal Script.
Windows 10
Not too thrilled so far. I liked the original TP build from November a lot better, but I hate the new Start Menu and Caption Buttons. When it's time to upgrade, I'll choose Windows 8.1, thank you very much.