Windows 7 was actually pretty clean. It was basically Windows XP with a nice look & feel. Also the last Windows without bloat everywhere (ok, IE)

But yeah, 2000 was somehow the apogee.

Plasma is pretty nice nowadays but I sometimes miss the simpler times of KDE 3.5

For the time, Win 2k was also amazingly easy to install (compared to win95, dos, Linux, WinNT). It really was a revelation.

I just realized that I probably used it or win2k3 daily for nearly 10 years.

Not just manual installation but fully automated remote installation too. From a manageability perspective, the 2000 series was a leap forward, with Active Directory and Group Policy. I always found it odd that Apple never even attempted to provide a proper solution for remote management of their OS and just left it to 3rd parties like JAMF. (I know they've made inroads into "enterprise" since then, but this definitely hamstrung them there for a long time)

Apple bought fleetsmith and has full GPO-style provisioning profile support for iOS, TVos, and macOS.

You can even do DEP so that certain serial numbers marked as "yours" will autoenroll/provision on wipe, on a blank/fresh OS.