I have the exact opposite experience as you. I have never once seen steam crash. My steam account is now 9 years old. I was absolutely stoked when I saw GOG Galaxy was trying to handle not only GOG games but games from other platforms as well. But my experience with that has been so bad. It’s fine for GOG games, but I’d much rather just add all my games into steam at this point. So as for stability, I don’t see any way that GOG Galaxy could ever beat Steam.
For Linux support, Steam is a DRM which is a detractor. But with all they’ve done with proton, steam input, steam deck OS… I’d say that Steam is definitely doing more for the Linux ecosystem than GOG.