KM, Right. I tried all the major ones: KDE Plasma, Gnome, Xfce, Mate, Cinnamon, several times over a period of time, but always came back to Plasma. My personal preference with respect to eye strain is: KDE > Cinnamon > Mate > Xfce > Gnome. I think Plasma's compositor is superior to the others. Cannot prove with numbers, though. In addition, I started liking the noto fonts which is the default font used by Plasma: they are crisp and sharp. Of course, I do a lot of Plasma configuration such as disabling baloo (file indexing), reducing the virtual desktops to one.