Windows is still better for gaming too. Take a look at some of your favorite games on Steam and see how many of them run on Linux. If they don't have Linux support they don't have SteamOS support either. It's a very small collection of games compared to the Steam games that run on Windows. There are workarounds but Windows is the better choice until game developers start including Linux support.
Windows is much more established, and will most likely continue to have more game support, and just be much better all around. I'm sure SteamOS will be nice, but it's going to be dedicated to gaming, which Windows can do and more.