My favs from 1st edition:
The Slavers series
Secret of Bone Hill
Ravenloft
The Sentinal/Gauntlet series
Against the Cult of the Reptile God
Tomb of the Lizard King
1E mods that are over-rated, IMO
GDQ - Pretty dull. The premise is good, and if it were fleshed out and some color added, it might not be too bad. The Queen of Spiders reprint did a bit to help, but not enough, IMO.
Keep on the Borderlands - I have fond memories of this adventure, who of us that were around back then doesn't? But, geez, it really is quite lame...
The DL series - Afraid I have to disagree with the poster that liked the DL mods. They were the precursor to all those really bad choo-choo train 2E mods that tried to tell a story while the PCs were pulled through by the nose to witness it. Blah. The books were a great read, though. All the other 1E/2E mods based on books or gold box PC games all pretty much sucked, too, IMO.
Tomb of Horrors - I had, and still have, a problem with deathtraps. Maybe it was fine for a one-nighter side adventure with PCs you don't give a hoot about, but I don't like playing that way. And to put a PC you've built up from 1st level into something like that is crazy.
3E? Well, from the sounds of it, I need to check out Freeport.
I liked Sunless Citidel (I don't play often, but I got to play through that, and it was fun). Haven't played, or even read all the way through, any of the other Adventure Path mods, even though I have most of them. They don't fit well into my campaign. Even with a bunch of work, they wouldn't fit very well, unlike numerous Dungeon adventures I've run from recent issues.
RttToEE isn't really my cup of tea, though it looks well put together, I just don't have the patience to run a single adventure that pretty much lasts the party's entire career. Dungeon crawls can be okay, as long as they don't drag on forever.