On the one hand I like GOG because it has no DRM and has better prices (in my country) than Steam and I have the feeling that on the one hand it follows more the open source philosophy than Steam itself, but Steam has helped enormously to play Windows games on Linux, so I haven’t really made up my mind.
On the one hand I want to buy on Steam for the convenience, but on the other hand I prefer GOG because (in my country) is cheaper. Which platform do you prefer and why?
To give an example, The Binding of Isaac: Rebirth is currently $15 on Steam with regional pricing, but on GOG it’s worth just $6.
Except you might want a client, both to keep your games in one place, and for extra features it can provide (like cloud saves and updates) - and if you’re on Linux, you’re excluded from that kind of stuff on GOG.