Recs.
Updated
Enlightenment, also known simply as E, is a compositing and stacking window manager for the X Window System. Since version 20, Enlightenment is also a Wayland compositor. Enlightenment developers have referred to it as "the original eye-candy window manager".
SpecsUpdate
Pros
Pro Nothing in the last 20 years beats e16
It's fast, doesn't use much resources, is highly customizable and is rock solid (I cannot remember it crashing). It's combination of simplicity and beauty is unmatched.
The default theme on e16 is kinda disappointing. Try B-42 or Dark-One.
Be careful if you enable Composite. It works flawless, but you can screw your menus when playing around with the transparent settings in the settings menu. Making a backup-copy of your .e16 preferences beforehand might save you some trouble.
Pro Lots of themes available
There is a large selection of themes available for the Enlightenment window manager, meaning that customization to one's preference is very straight-forward.