MATE is an open source user interface for computers running the Linux operating system. It is designed to provide a modern and attractive desktop environment that works well on both traditional PCs and mobile devices. It is based on the GNOME desktop environment, and offers a range of features such as custom themes, a file manager, and a range of applications. It can be used on a variety of Linux distributions, including Ubuntu, Fedora, and Red Hat Enterprise Linux. MATE is easy to use, provides a secure and stable environment, and is highly customizable.
Budgie is a newcomer to the desktop game. It sits on top of GNOME to provide a more intuitive and updated look and feel. It is not yet a good replacement for MATE (it might be in the future), mainly because it runs considerably slower and has some unresolved bugs at the time of writing. Promising though.
GNOME
Xfce
KDE Plasma
Cinnamon
LXDE
LXQt
Budgie
Enlightenment
Lumina Desktop Environment
EDE
CDE (Common Desktop Environment)
Elokab
Trinity Desktop Environment (TDE)
UKUI
XFCE and MATE follow a very similar design philosophy and both are similar in the way they feel to customize. Both use the GTK+ toolkit and both are relatively light on resources, making them a good choice for older or lower spec computers.