My favorite dungeon types are old school dungeon crawls. Just a place underground with a bunch of levels and a bunch of halls and rooms on each level.
As a DM, the one I’ve enjoyed the most was running Return to Undermountain and Expedition to the Ruins of Greyhawk back to back as one story arc. It was a blast and I had a lot of fun as the DM in that arc. My second favorite DM track was running the Speaker in Dreams module. I loved the illithid behind the plot, Gharaleth Axom.
There have been so many, it’s really hard to pick. Here are a few highlights, both as player and as DM
This is a question that is kind of vague. If it’s talking about pre-defined characters such as Drizzt or Bigby or Tanis Half-Elven or whatever, I don’t really consider them PCs. Even when I was involved in groups running the original Dragonlance modules, I didn’t really consider them PCs. They were NPCs that we’d temporarily stepped into playing.
It’s a tossup between three of them. First, is Endeleban Losteast (Delban). He’s a wizard and former Aes Saidarr of Cormyr. Second is the paladin Terun Eastmore. As a paladin of Helm, he followed a path slightly adjacent to what most paladin’s might call correct.