Lumina Desktop Environment - Lumina is a lightweight, BSD licensed, standards-compliant desktop environment based upon Qt and...
i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
KDE Plasma Desktop - Plasma Workspaces is the umbrella term for all graphical environments provided by KDE.
dwm - dwm is a dynamic window manager for X. It manages windows in tiled, monocle and floating layouts. All of the layouts can be applied dynamically, optimising the environment for the application in use and the task performed.
LXDE - Why will you like it? Less resource needs. You can use it on your less-pricey embedded board or salvaged computer. Component-based design. Don't want something in LXDE, or you don't want to use LXDE but only part of it?
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.