Games

It depends on what aspects of an open world are important to you.

Exploration is at the top of my list, and Skyrim is a good example of doing it well. Its world is full of unique things/places/characters to find, whether through an NPC's directions, or a roughly sketched map picked up while adventuring, or following your curiosity toward an area that looks interesting, or chasing a fox, or simply by wandering off the beaten path.

Map markers appear after you've already been somewhere so you can find your way back again, but since most of them are hidden until then, they don't spoil the experience of discovery.

And, when you find something, it's often genuinely interesting. Not yet another copy/paste monster fight or "hold the button to follow your witcher sense to the lost thing" quest. Not just checking off a task list item (or pre-placed map marker) so you can rush to the next one. The experience itself is rewarding.

Mind, I have criticisms of Skyrim, but it did exploration and environments (including sound) very well, and I wish more open world designers would learn from it and build upon its strengths.

EDIT:

I would love to play a game that reached or exceeded Skyrim's bar for exploration and environmental immersion, Breath of the Wild's bar for freedom of movement and wildlife, and The Witcher 3's bar for characters and story.