Hacker News Reader

I know it's rhetorical, but... openSUSE

Slackware: Plasma 5 was just moved from testing this week in Current (for the upcoming Slackware 15).

Kubuntu, KDE Neon

SuSE.

SUSE Linux Enterprise Desktop currently ships GNOME (and IceWM) and doesn't even mention KDE:

You may be thinking of openSUSE.