Since 90% of my games are on Steam, I don't see the point in getting it somewhere else. I use 3 computers at home, I want family sharing and in-home streaming that only Steam has. The only other store that has any reason to exist is GOG because they offer offline installers. All the rest of the launcher arsenal is just useless clutter with no useful feature whatsoever in my opinion.
So it's either Steam for me, or I'll obtain it through "other sources" while Ubisoft decides to launch a Steam version.