BOTW had some surprisingly good forests. The Lost Woods was nice and atmospheric, full of fog and spoopy trees. And there was the island of darkness which was pure fun. Running around an inky void with a torch, lighting signal fires, fighting a giant monster who you can barely make out as a silhouette, it was the closest the game got to feeling like an actual adventure full of mystery.
Myself, I love a good forest, which is a shame because they're rarely done well. The Witcher 3 had some amazing forests, properly lush and vibrant, with leshens wandering around to fuck your shit up.
And a nice abandoned cum ruined castle that is half exposed to the elements is good too. So for one section you're crawling through a hallway filled with rooms of aged and rotting furniture, and then you're on the battlements and they break open to reveal the mundane elements of the castle like the barracks underneath. Dark Souls games do this well, and BOTW, again, one of the few decent parts of the game was Hyrule Castle, especially the way the music changed depending on whether you were inside or outside.
Exploring is fun. Automaps, quest markers, and floating waypoints can fuck right off. Have the NPCs give proper directions. I hate casuals.
> Anyone else like sewer / cistern type settings or am I in a significant minority?
Only if they make the sewers relative to the overworld, and you can use them as shortcuts or ambush points or whatever. If it's just a generic sewer level then it can fuck off.