For reference:
For window managers, see Window Manager Showcase For stylized screenshots, see Rice Showcase
For OS specific changes to desktop environments, jump here
Popular Desktop Environments
Unity (Personal Favorite)
GNOME (v 44)
KDE Plasma 5
Cinnamon
MATE (GNOME 2 Fork (means derivative))
Pantheon
Budgie
Enlightenment
Lightweight
Xfce
LXQt (LXDE)
Less popular
Deepin (20+)
Deepin (15.11, personal favorite)
Cutefish
OS Specific Adjustments
Manjaro GNOME Edition
Manjaro GNOME edition allows changing GNOME layout. This screenshot was prior to GNOME 40, but I think they should still have it.
Zorin OS
Zorin OS is an aesthetically themed OS based on Ubuntu GNOME. It also supports multiple layouts
Ubuntu MATE
Ubuntu MATE also allows changing layouts
Ubuntu
Ubuntu adds a number of extensions on to stock GNOME to brand it. I have listed a few differences between Fedora’s stock GNOME and Ubuntu here: Converting Fedora to Ubuntu
Pop OS
Pop OS is migrating from GNOME to their own COSMIC desktop environment. A major distinciton from Ubuntu’s appearance is the use of a tiling window extension named Pop Shell.
I listed some of the differences here: Converting Ubuntu to Pop OS
