Xfce is described as '(pronounced as four individual letters) is a free software desktop environment for Unix and other Unix-like platforms, such as Linux, Solaris and BSD. It aims to be fast and lightweight, while still being visually appealing and easy to use' and is a very popular desktop environment in the os & utilities category. There are more than 25 alternatives to Xfce for a variety of platforms, including Linux, BSD, Windows, Mac and Linux Mobile apps. The best Xfce alternative is KDE Plasma, which is both free and Open Source. Other great apps like Xfce are GNOME, Cinnamon, Noctalia and MATE.
Whilst KDE and XFCE are both highly customisable, KDE is much more prone to bugs and is also uses a significantly larger amount of resources relative to XFCE.