I tend to prefer the Steam version if I have both, mainly as you say for acbievments and keeping my playtime all in one place. But also the community forums and guides are nice sometimes, and easily accessible with the steam ui.
GoG I’ll pick (and mainly purchase towards) older games and nostalgic favorites where lack of drm feels more important to me. Those often don’t have achievements and such anyway.
Funny enough, I get pretty annoyed about that playtime tracking thing. I wish there was like a last.fm scrobbler but for games. Before my SteamDeck, I rebought several games on Switch because I liked the portability. So now my playtime on those is split across multiple devices. Ah well, truly first world problems.