I don't know about running KDE in a non-systemd distro. I wouldn't do.

I run Void in the last year and I tested major Desktop Environments: Gnome,KDE, XFCE, Cinnamon.  As I remember KDE has some systemd-dependencies, some KDE module were unusable in Void. There are rumors that more systemd dependencies will be added in KDE. And each update on KDE packages can bring problems, for a rolling release such as Void is not really a good option. That's a bit annoying for the end user.

If I would run KDE, I would choose OpenSUSE or Fedora. OpenSUSE is a better choice than Fedora, Fedora is unstable, is just the testing bed for RHEL. I would not use it. But in OpenSUSE, KDE was the default choice for a long time, many vets of OpenSUSE run KDE. And of course KUbuntu. I don't know about the other 'n variants, I don't think they really matter.

XFCE and Cinnamon are the wisest choices in my opinion. They work everywhere. If you want Wayland than labwc is an excellent choice . It just works in Devuan .