Ok I suggest
Dohna Dohna Let's do bad things together
It is not on gog but you can buy it drm free on mangagamer.
One of the best game I ever played and I played all the games you mention as good.
Both the VN par of the game so the writing and the gameplay (it's not just a VN) are really really good.
Also some games are like you say slop but some are actually good even when they are not masterpiece, like I think Huniepop is a good game (not a masterpiece but still good) and it's on gog.
I think you just decided they are all slop because you tried some bad games.
On my end I think one of the few things good about gog is that they don't discriminate between sex and not sex games, I think modern society is way too scared about sex stuff. There is nothing wrong with it. Some will argue "think of the children" but let's be honest, children are not interested, those filters are meant for adult that are way too ashemed of something that's part of life
alaric.us: While some violent games and horror games are actually great games, the vast overwhelming majority of porn games are low effort slop the only purpose of which is to extract a few dollars from sexually-frustrated basement dwellers.
Alert me when there's a sex game of the level of quality and cultural importance of Doom/Diablo/Hitman/Witcher/etc. I'll be sure to buy it and play it.
Until then, maybe we should be keeping storefronts free of trash, regardless of whether it's trash that emphasizes sex or trash that emphasizes something else.