What is your favorite module/adventure for pre-3E D&D?

[Voros]

UK 2 The Sentinel and UK 3 The Gauntlet, two linked adventures inextricably linked to AD&D.

I ran UK 1 Beyond the Crystal caves for my friends using RQ3 where they played idiot evil goblinoids in what was probably our funniest ever roleplaying experience

I'm a fan of the TSR UK modules and Beyond the Crystal Cave is one of their best. Was able to snag a used copy for a reasonable price.

 

[Jkitz]

There is a great alternate sequel to G1-3 by Expeditious Retreat Press - AA#36 The Aerie of the Cloud Giant Strategos
Where the cloud giants are behind it all. I've run it at a con and enjoy it. You can purchase and also watch a video I recorded about it at the above link.

My favourite that I have used over an over is AA#1 The Pod-Caverns of the Sinister Shroom
Great winding passages, strange things encountered, great new monsters.

 

[Akrasia]

There is a great alternate sequel to G1-3 by Expeditious Retreat Press - AA#36 The Aerie of the Cloud Giant Strategos
Where the cloud giants are behind it all. I've run it at a con and enjoy it. You can purchase and also watch a video I recorded about it.

This looks interesting. Is it meant to replace D1-3?

 

[Jkitz]

This looks interesting. Is it meant to replace D1-3?

That is the intention yes. I tie in the cloud giant in Steading a little more (well mostly his magic sword -- I gave it to the characters when I ran it at a con last October) and yes probably reduce the drow in G3.
The Floating cloud island actually has a mini-hex crawl to it and the cloud castle, Napathantos is made out of solid "cloud-stuff."