I've settled on XFCE. It just works. You have to turn too many knobs to make it work on weird DPI / screen sizes, but other than that, it's fine.

Recently, I fired up Win 3.11 in 1600x1200@256 mode to run SimAnt, and was pretty shocked at how much better it felt than most modern operating systems.

I kind of feel like the start menu + task bar were a mistake now.

It is nice having the bluetooth + network icon somewhere accessible, but maybe <ctrl>-space should just pop up a thing that lets you type program names + also temporarily hide all windows over 10% of the screen or something? That'd solve the problem of trying to find program manager to run a second program. Also, the windows in windows approach of program manager wasn't great. Still, it's better than most things out there these days. The icons are so... clean.

In my opinion, the versions of Mac OS with the Platinum theme (8, 8.5, 9) have aged quite gracefully. It's clearly not modern, but it also doesn't feel particularly old or kludgy or anything, and it's quite clean relative to modern desktops.