GNU/Linux is the most important operating system the world has ever known. It runs everything from traffic lights, to web sites, to the largest number of phones in existence.
[Android is not an operating system despite what the poorly informed Codecademy people might say.]
That’s right, some variant of Linux (or UNIX) is at the core of pretty much every device on the planet right now except Windows computers, and even that is changing.
Which Linux Distro Should I Use?
That really depends on what you are doing with it.
Linux Mint Cinnamon is current the best Linux workstation distribution. Mint is an Ubuntu distribution itself and 100% compatible with Ubuntu.
Ubuntu server is currently the best Linux server distribution.
Kali Linux is the best mainstream security distribution currently available. Usually professionals run this from a live boot usb rather than installing in on anything – especially given how frequently it is updated.
Raspbian is all you should really get for Raspberry Pi. The number of packages and the
raspi-config utility are really the best way to get up and running and maintain it. I recommend getting only the Lite version because most all of the graphics applications are absolutely useless.