Valve is the only company i trust to handle my games. Them being bought by Microsoft would ruin their entire business and would probably not happen because Cartel offices have to say something about that.
And that's why Steam gets my money instead of GOG.
That said, apparently Heroic has some kind of agreement with GOG where they get paid for sales, so maybe by buying games on Linux through Heroic you'll get GOG interested in Linux support.
Sure, but it's at least an avenue to a decent launcher for GOG games on Linux. I still prefer Steam, but Heroic is good enough that I'll consider buying a few games now and then.
Yeah when something is available cheaper there shure but besides that i trust valve more and don't buy from anywhere besides ich.io steam or gog, depending where its available/cheapest