All Linux distributions with a GNU userland
Ranked in these QuestionsQuestion Ranking
It is a Unix clone.
Pro Many different desktops to choose
Just use whatever you want. Some are lightweight, others are full of extravagant features. There is a flavor for each taste.
You don't have to pay anything.
Uses the same userland as other GNU variants.
It's only a clone and some things work differently.
Con Many distributions
There are just too many of them to know.
Con Often limited by decisions of the Kernel developers
Support for the latest features in Linux is often limited by their kernel developers, for example, Nvidia once had added patches to support Optimus on Linux, however, the kernel developers rejected those patches resulting in still no official Optimus support for Linux.
Con No interface Guidelines
Since there are plenty of X11-Desktop environments and two big Widget Toolkits, every app works and feels differently.
Con Frankenstein OS
The whole OS is mixed together with software from different sources.
Con GNU Copyleft
The coplyleft in the GNU licenses make it unattractive to many developers. It s also impossible to port GPLed Linux improvements to other more open operating systems like BSD or Haiku.
Con Most Distributions are not LSB-conform
The most Distributions don't follow the Linux Standard Base which results in different package formates, package management tools, bootloaders, init-systems or even filesystem hierarchy standards.
Con Most 3D drivers are not as fast as their Windows counterparts
The only display driver that comes close to their Windows counterpart is the nvidia driver. Both AMD and Intel drivers miss a Control Panel on Linux to adjust more settings than just your resolution they also usually much slower than their Windows counterparts.
Con No graphical user-interface
As the most unix systems this also comes without a graphical user interface by default.