Halls of Beol-Dur (Dragon#41) by Dave Luther et al: One of the all-time classic dungeon crawls of the first edition era. This one has it all. This is the essence of 1st edition.
Seeking Bloodsilver (Dungeon #59) by Chris Perkins: Great map to a fortress located in the shadow plane and a solid adventure. I've reused this map a few times and I never tire of it.
Raiders of Galath's Roost (Dungeon #87) by Skip Williams: Skip's writing is awfully dry in many of his adventures - but his crunch and design is bang on. The map is great and this one plays
much better than it reads.
Mad God's Key (Dungeon #114) by Jason Buhlman: Jason Buhlman's first published adventure. Several years later, I'm playing Pathfinder. Well done Jason.
The Whispering Cairn (Dungeon #124) by Erik Mona: This intro into the
Age of Worms was an awesome romp. Just the right amount of dungeon crawl, broken up by matters outside of the dungeon -- and then back in -- at just the right time. A clinic in proper adventure pacing.
The Three Faces of Evil (Dungeon #125) by Mike Mearls: This second installment in the Age of Worms was extremely memorable. Great fun.
There are no "least favorities". There are several hundred adventures in my *almost* complete Dungeon collection I have not run. I'm sure out of those -- there are some extremely iffy adventures. I'm also just as sure that there are probably a few that I have not ever played -- and have not read in a decade -- that probably deserve to be in the above list. Some day? I'll find them and revise my list.
That's the beauty of
Dungeon Magazine. It's a gift that keeps on giving for years and years to come.
God, I miss it.