Win32 generally means the old school Windows API. Even when compiling as 64 bit.

And I'm not worried about deprecation on that front anytime soon.
Microsoft pivoted back to promoting good old C++ and Win32 on at least equal footing with their "modern" APIs.

Well, they do all have their issues one way or another. Some more so than others.

I don't even see Windows 7 being all that much better than any current efforts. If Win10 wasn't so full of telemetry, it would actually be better than Win7, IMHO. (Apart from the flat, butt-ugly GUI.)

My personal candiate for "Last Good OS(TM)" would probably be a mid noughties Slackware distro with KDE 3.5.
F#cking rock solid distro, and KDE3.x was the best looking desktop on any platform.
Of course, there was nothing remotely beginner (read: basically anyone but professional programmers) friendly about Slackware, so on the General OS Shittiness Scale, I admit even that did have a certain inescapable whiff of poo scent.

As long as Windows has syswow64 (system32 in reality) it should still be able to run all your 32 Bit apps. In the event Microsoft deprecate syswow64 they'll probably just replace it with some kind of emulator. It's all about dll files you see.
The UI is exactly what I'm talking about. Windows 10 has been out for almost 10 years and Microsoft still hasn't decided what they want to do with it. Wasn't there supposed to be a subscription service for it or something. There's too many settings you don't want and not enough of the ones you do want. Windows 7 was good because it was easy to use and had only one control and everything you needed was in it. Windows 10 has a privacy settings tucked away in it's flat settings menu. But it also has file and folders privacy settings in a completely separate menu. All menus and BS that's Win 10.
If it's not appropriate for public consumption it can hardly be called good.

Not a proper consumer OS, true.
Still the best in many ways, though. Slackware for stability, KDE 3.x for good looks.
Every GUI since KDE 3.x has been a downhill slide, IMO.

I think Windows 2000 SP4 would be my "last good" Windows, on account of it being the last one that didn't need online activation of any sort.

None of them have ever really "needed" online activation if you get my drift. But I know what you mean. For me Windows 2000 was a strange one. Very stable and very good but it sucked when it came to playing games. EX was much better for games but was no where near as solid. Maybe you just can't get gaming and stupidity to really mix.

Anyway my favorite OS's in order from best to worst are Win7 win98 SE DOS with Win 3.11 on it. and that's it really.