It's my primary platform but I use all of the PC platforms.
But I still prefer Steam over other platforms for the following:
+ Valve doesn't have as many funny policies or behavior as others, still a true gaming company
+ Most refined refund process of any platform, period
+ Often very good prices
+ 3rd party keysellers also direct me there
+ I like the ways you can organize your library and the way games are executed from Steam
+ Stuff around the edges like the cloud save implementation, the installation process for games
But I still prefer Steam over other platforms for the following:
+ Valve doesn't have as many funny policies or behavior as others, still a true gaming company
+ Most refined refund process of any platform, period
+ Often very good prices
+ 3rd party keysellers also direct me there
+ I like the ways you can organize your library and the way games are executed from Steam
+ Stuff around the edges like the cloud save implementation, the installation process for games