Top of this list used to be particular versions of Ubuntu
Summary: GNU/Linux "market share" in Steam grew by a quarter this past year, boosted by SteamOS perhaps, but watch the trends in distributions; even the Ubuntu-based distros aren't near the top (and SteamOS moved from Debian to Arch, so expect Ubuntu to stagnate further)
Microsoft- and Apple-sponsored Western (or English-speaking) media chooses to ignore that or treat it as irrelevant (a racist disposition in its own right)
A choice between "masters" (or "master race") is a false choice that results in mass exploitation and ultimately eradication (when there's little left to exploit)