I'm currently writing this on the MATE desktop. I started with linux on the gnome 2 desktop, so it only makes sense. A long time ago I used Xmonad (a tiling window manager) but tiling has less appeal for me now. If I need/want a lightweight solution, I use CWM (https://en.wikipedia.org/wiki/Cwm_(window_manager), which was originally developed on OpenBSD, but is usually available across different Linux distros and BSD's.

I've tried pretty much every DE/WM under the sun at this point, and would be interested to know what you use and why