i3 - A dynamic tiling window manager designed for X11, inspired by wmii, and written in C.
Lumina Desktop Environment - Lumina is a lightweight, BSD licensed, standards-compliant desktop environment based upon Qt and...
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.
KDE Plasma Desktop - Plasma Workspaces is the umbrella term for all graphical environments provided by KDE.
Openbox - Openbox is a highly configurable, next generation window manager with extensive standards support.
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?