Pondering other worlds, whether those be the distant worlds in our own universe, or the worlds we can enter through the stories of others.
...
Speaking of which, here are some worlds/stories that I like, in no particular pattern or order (though this is probably in need of some updating):
The Cosmere
Avatar: The Last Airbender
The Legend of Zelda
The Xenoblade Chronicles series
Ender's Game, Speaker for the Dead, and adjacent books
Project Hail Mary
The Remembrance of Earth's Past
Dune
Interstellar
Arrival
Inception
Tenet
Princess Mononoke
Castle in the Sky
Fullmetal Alchemist
Star Wars
...And probably a bunch of others I'm forgetting. This list is not comprehensive.
Children of Dune at first is amazing. I love the first two thirds, but the last third ruins it very much for me. It's probably my least fave Dune book.
However, I love Dune Messiah to death. First time I read it, I hated it, second time I loved it.