It's honestly shocking to not see Desert Stalker, Oppai Odyssey or Artemis in the conversation. Those are also S tiers I'd put up there with Eternum in every conversation, albeit how they're ordered would be down to preference. For example Oppai Odyssey is undeniably a stellar game all around, but it does remove player agency for the sake of the story. While this would lower it's appeal or some people, I'd say it's undoubtably a very clear cut above 90% of AVN's out there due to every other factor. I've also never put tremendous weight on music, although I understand it's appeal. It's all subjective after all.
There's also games like Unraveling August, STWA Unbroken, The Missing Part and very recently Artifice; among others, that I think are and will continue to be incredible games as long as they maintain their consistency and actually get updates.
I've dropped Sicae, MBIML and New Horizons previously due to their writing, but I find myself coming to try again since I'm struggling to find new gems. From what I understand, there's a good story here, but something about the writing and dynamics makes it hard to get through for me. Can't say the same for any of the aforementioned projects.