NixOS desktops
NixOS has only KDE listed as DE, but that's only the default desktop included in the live cd.
You can configure many DEs and WMs!
The current stable release (18.09) provides:
Enlightenment Gnome 3 kodi Lumina LXQt MATE MaXX Plasma 5 (KDE 5) Xfce
2bwm afterstep Awesome bspwm dwm evilwm exwm fluxbox Fvwm herbstluftwm i3 icewm jwm metacity mwm notion openbox pekwm qtile ratpoison sawfish spectrwm stumpwm twm windowlab windowmaker wmii xmonad
They might not all work well, but you can enable and test them out with just one line of configuration!
services.xserver.windowManager.i3.enable = true;