Favorite Dungeon Type/ Location

The Lost Necropolis.
It’s a concept that can be applied to nearly any setting. In the realm world, it’s a city of the dead buried in the sands or lost in the mountains… or it’s the underground that was destroyed in an earthquake and the new city built on top of it. In science fiction it’s the derelict starship drifting dead in space… or the ancient civilization that left only empty monuments. In fantasy, it’s often, you know, a Lost Necropolis.
I like it both because it’s flexible (is it full of undead? Do cultists now worship Uhluhtc in its dust tombs? Was it turned into a bandit hideout? ), and iconic. Indiana Jones, Space Marines, and Gandalf have all had their turn in the Lost Necropolis, so it’s easy for players to envision their heroes doing so as well.

It’s also a great chance for worldbuilding. Who built it? What were their burial traditions? Why was it lost? Who found it, and what are their plans for it? You can have a typical dungeon-stomp, but you can also craft a narrative that fills in the dark corners of the campaign setting.