When comparing SteamOS vs LibreELEC, the Slant community recommends LibreELEC for most people. In the question“What are the best operating systems for a Home Theatre PC?” LibreELEC is ranked 3rd while SteamOS is ranked 4th.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Native graphics processor support
The OS natively supports Nvidia, Intel, and AMD graphics processors.
Pro Streaming service integration (under development)
Valve is in talks with streaming companies such as Spotify and Netflix to bring their features to SteamOS.
Pro For entertainment, it just works
What media center software do for videos, it does for games (and later videos).
Pro Free and easy to install and use
Pro Ease of use!
Ease of installation and small memory foot print. Boots straight into kodi. Lighting fast operation. Huge support network. Regular updates! Follows development of kodi closely.
Pro Runs on a USB stick or SD card as small as 8 gb
Check here for full specs and requirements.
Pro Runs well on a Raspberry Pi
Runs cooler than Kodi on a Pi.
Cons
Con Hard to install
If you've installed Arch you're probably fine, but for those used to simple installs like (Ubuntu to name just one) you should prepare some patience, determination, and painkillers. Good news is, it's getting better (it's very young).
Con Not built around the desktop experience
SteamOS is, first and foremost, meant to act as a gaming console - it doesn't ship with even some of the most basic applications, such as a file manager or image viewer. As a result, using SteamOS as your primary operating system would require a fair bit of work.