Linux

I'll preface this with: If you like Windows and don't particularly care for Linux experiences, that's ok. Not everyone needs to use Linux - the world is more interesting with variety.

For me, I hate when my computer does things that I don't tell it to. I also hate ads. These, along with but really using it for a decade were deal breakers for me with windows.

Some things that Linux has that Windows does not:

• Native package managers: Realize that you need to use an image editor and don't have one installed? You can just install it with your distro's package manager. It will usually take care of any dependencies and make it easy to update or uninstall if you decide you want to. Some distros have particularly massive offerings in their package repos.
• Freely customizeable UI: Tired of how your system looks and want to try something else? Install a tiling window manager through the package manager. Or, maybe Gnome or KDE or XFCE. Huge amounts of customization in your GUI are possible.
• Programming: Interested in programming? Install some development tooling through the package manager.
• Embedded Programming: Interested in programming but want it to be more physically tangible or automate parts of your home? Setup the Arduino IDE, or Mu, or go old school and use vim/emacs. Then, compile and push it out to your microcontroller. Or, you can use something like Blinka on a Raspberry Pi or similar SBC and directly interact with sensors and devices across the built-in GPIO pins.
• Tinkering: Enjoy just poking about? The kernel being open-source means that its APIs are well documented and you can find lots of tools to tweak your system's behavior or do so yourself.
• Job opportunities: The Internet runs primarily on Linux servers. If you're interested in tech work, getting familiar with Linux can't hurt.
• Tux: What is Windows' mascot? A window? How about an awesome penguin? Distros and DEs often also have their own, like a chameleon, wildebeest, or dragons (2/3 of the examples can readily smash a window while the other one could at least get an E for Effort and scream at it in german).

For distros that work well with steam, I definitely suggest Linux Mint or Ubuntu for beginners. They're just way more "batteries included". However, if you could also give SteamOS, the distro developed by Valve (on top of Debian) a try and it will probably work quite well.

Most of all, have fun, whether you decide to take Linux for a spin or not.