They are desktop environments, normally not inetrfering with X-window stuff. Choice is a matter of taste, personally I like+use KDE. Most "gnome" apps run under KDE and vice versa, but don't take it for granted.
If you compile from source GUI'ed apps you will find that you will need most libraries installed (GTK, Qt, KDE...) to build properly, no matter which desktop you run.
The revolution cannot be a lever, or an essay, or tablaeu, or embroidery. It cannot proceed mellowly, piece-by-piece, gently, devoutly, simply and humbly.
Mao Zedong