I also used Windowmaker for a really long time, but stopped when a few years ago it was incompatible with a few of the applications I use (e.g. gaim (now pidgin) would crash very often, and some more annoyances I forgot about).

I especially liked docking applications/icons, its good support for virtual desktops and especially the many wmXXX applications that did one job well, in the space of a 64x64 pixel tile.

These days, I mostly resort to the "standard" gnome desktop with whatever it uses and resort to something very lightweight such as fluxbox on resource constrained machines.