XP or 7. Also win 98 wasn't so bad. That machine had problems but usually it wasn't the operating system.

Never mattered to me, once I installed http://toastytech.com/guis/bob.html they all looked the same. Apparently a new version of Bob is due to be released later this year. http://en.wikipedia.org/wiki/Windows_8 so joyous times are ahead.

Windows 7 is the first Microsoft OS that didn't leave me feeling like I wanted something better. With 95/98 it was better memory management and proper multi-tasking and then with XP it was tighter security.

I have tried many Windows OS in the past including some classic one. Last year, I used Windows 7 since it is the latest from Microsoft. But as the time goes by, Windows 7 seems slower and slower. At the end of the day, I reinstall my beloved Windows XP. So far, I have no problem with Windows XP compare to Windows 7.

You can keep 7 for a long time, in case you don't like 8 or 9. I think it will be supported until 2020.

No. Because a lot of people hated Vista and that was more advanced than the commonly preferred XP. It's about which version of Windows people are happiest with. That's the question I'm answering anyway.

I didn't even realise how much XP annoyed me until I upgraded to it.

Then it is still a matter of opinion, not a "fact" as you said. I still feel I found less new annoyances in e.g. Win9x and WinXP when they were new, than I've had with Win7, especially related to PC gaming (to stay on the theme of the site).

That is not to say Win7 isn't quite good evolution, but overall it has left me with a "meh" feeling, while with 9x and 2000/XP I was quite overjoyed about the switch, even though 2000/XP broke DOS gaming compatibility for some time. But e.g. NTFS replacing FAT32, and overall home Windows finally moving to NT core, more than made up for it.

For me personally, the biggest positive thing about Win7 is that it is the Windows OS that seems to finally move home users to a 64bit OS. About time.

I think that it's quantifiable that Windows 7 is the better OS. The fact that it's the most advanced is a part of that, but ultimately it's about the user experience delivered. Which is what I meant by 'happiest'.

Too bad developers still haven't, but then, most things don't really need the 64bit precision or extra memory.

I think Vista would have given you a more 'wow' feeling than 7, which is basically an improvement of Vista, but didn't bring much new (well, compared to Vista) to the table. Too bad driver developers failed so bad with the new driver model, otherwise the OS would have been remembered as good, by the general public idiots (idiots because they thought Apple's ads really represented the situation with Vista), at least.

8 will bring another 'wow', even though most things are really hidden behind the whole 'I hate Metro' crap.

EDIT: I expect 9 to be an improvement of 8, and 10 to bring a lot new features (including setting the new ReFS file system as the default one).

Windows 2000 Pro was pretty damned good, actually. Win 98 (not the SE) caused me the most headaches (never used ME).

I have to say that I was one of the (apparently rare) happy users of Windows Me.

7.
Vista hangs up a lot on me, and XP doesn't natively support phone tethering.

7 all the way.

It keeps getting slower and slower in my case too. And I installed it only few months ago. Vista was like a speed demon in comparison with Windows 7. I remember having Vista installed almost 4 years and it was much faster than Windows 7 after just few months.

Same here. I had many problems with both 98 and 98SE versions (BSOD and crashes all along) and were greatly reduced (though not all) when I installed ME. Although I am aware that Alexrd and I are part of a very small minority (but a select one :D)

Windows 2000

NT4 + more refined interface and gaming compatibility.

Things went downhill after that.