Since around a year or two I've been using i3 tiling window manager together with the xfce4 services as my desktop environment and I'm quite content with the result. The i3-wm can be installed on top of the xfce4 DE without any package conflicts. Such a combination allows to have both DE at the same time and share common settings and applications between them.
I can't remember exactly why I have chosen the i3-wm as my window manager but maybe it's because I have read that i3-wm has vim style movement keyboard shortcuts. As far as I'm a vim user I decided to 'take it for a spin'.