I use Linux on my media PC. I actually switched to Windows for a little while, because it was preinstalled. I only switched to Linux because I wanted to SSH into the machine, run OpenVPN, duckdns updater, home automation scripts, etc. I was just more comfortable in Linux.

I run Plex Server, Plex Home Theater, Spotify desktop app (in the background), and EmulationStation. I've been very happy with it so far.

It would be nice if I could get Netflix integrated, but I just use my phone and a Chromecast for that.