Note - This post is part of the 30 Day D&D Challenge.
Day 12 - Favorite Dungeon Type/Location
Typically, whichever one I'm currently in. I do have a slight preference for traditional dungeon crawls, but only because it took so long for me to get in one. The first D&D campaign I played in, while an excellent campaign, never had any dungeons in it. As a new player, I was itching to get into my first dungeon and fight my first dragon, but it would be a long time before I experienced either.
When running a game, a lot of my dungeons seem to be of the "abandoned lab" variety. Players find an old, usually underground research facility, which is still populated by the weird experiments of a long-dead scientist. "Zombie Cyborgs from Outer Space" is a prime example, but "Death By Chocolate" also has elements of this trope, as do several areas in my old NeverWinter Nights module, Itropa.