I am currently on a Mac but I have been switching between Mac, Windows, UNIX, and BeOS since 1991. I generally find things to like in all of them.
But what Microsoft has done with mandatory updates and forced telemetry is unacceptable to me. And because of that, Windows 10 is the first version of Windows that I have not installed since the release of version 3.0.
I installed W10 just to try it, to confirm that it was as terrible as everyone said. It was, and I decided to switch back just a few days after it had silently deleted the files required to undo the uninstall :(
I was under the impression that Windows 10 is quite decent except for the specific issues I mentioned.
As for BeOS I really liked it. It was very stable and fast if the hardware you had was supported[1]. It had great multi-CPU support, came with a BASH shell, and also BeFS - which with its support for arbitrary user defined metadata, which made things like email and music queries very interesting.
The downside of BeOS was that it didn't attract any big third party apps and that it was a single user operating system.
[1] I ran BeOS on a Gateway Performance 450 with the following (from memory) specs: 450mhz Pentium 3, 384MB of RAM, a nVidia TNT graphics card, and a Promise Ultra 66 IDE card. I eventually moved away from it when I upgraded to a Pentium 4 computer with RD-RAM.
But what Microsoft has done with mandatory updates and forced telemetry is unacceptable to me. And because of that, Windows 10 is the first version of Windows that I have not installed since the release of version 3.0.