Stormonu
NeoGrognard
The ones I've enjoyed over the years that I've run straight up have been
S2 - White Plume Mountain
I6 - Ravenloft
A2 - Secret of the Slaver's Stockade (I've run A1-A4, but A2 was the only one that was "enjoyable")
L2 - Assassin's Knot
U1-U3 (both the original and in Ghosts of Saltmarsh)
C1 - Hidden Shrine of Tamoachan (but I had to do a lot of reading up on MesoAmerican culture/mythology to get there)
X1 - Isle of Dread (though by its nature it needs the DM to fill in a few spots)
Lost Mines of Phandelver - hands down, D&D's best starting adventure to date
More often than not, over the years I've used old modules as reference material for designing my own adventures and pulling out bits and pieces or as a seed for an encounter or campaign idea in my own games.
I'm going to go a step further too, but put these is spoilers since they don't meet the original question's criteria.
I've had several that I had to significantly modify to be enjoyable, but they had a good skeleton.
There's been some that I thought were going to be great but fell apart running them
And some are just stinkers
S2 - White Plume Mountain
I6 - Ravenloft
A2 - Secret of the Slaver's Stockade (I've run A1-A4, but A2 was the only one that was "enjoyable")
L2 - Assassin's Knot
U1-U3 (both the original and in Ghosts of Saltmarsh)
C1 - Hidden Shrine of Tamoachan (but I had to do a lot of reading up on MesoAmerican culture/mythology to get there)
X1 - Isle of Dread (though by its nature it needs the DM to fill in a few spots)
Lost Mines of Phandelver - hands down, D&D's best starting adventure to date
More often than not, over the years I've used old modules as reference material for designing my own adventures and pulling out bits and pieces or as a seed for an encounter or campaign idea in my own games.
I'm going to go a step further too, but put these is spoilers since they don't meet the original question's criteria.
I've had several that I had to significantly modify to be enjoyable, but they had a good skeleton.
RQ1 - Night of the Living Dead (The part with confronting Jean doesn't pan out as it reads, nor does the final battle in the crypt.
DCC4 - Bloody Jack's Gold (3E, Goodman Games) (My party was too high level, so I had to up the stats, but they loved it, especially the Ziggaraut fight)
X2 - Castle Amber (Its quirky, and the whole second part in Averoigne has to be fleshed out before it can be finished; it's why I bought the 5E OAR version, as it's done the work for you - but I haven't had the chance to run it)
DCC4 - Bloody Jack's Gold (3E, Goodman Games) (My party was too high level, so I had to up the stats, but they loved it, especially the Ziggaraut fight)
X2 - Castle Amber (Its quirky, and the whole second part in Averoigne has to be fleshed out before it can be finished; it's why I bought the 5E OAR version, as it's done the work for you - but I haven't had the chance to run it)
There's been some that I thought were going to be great but fell apart running them
B2 - Keep on the Borderlands (everyone dies in room E18 that I've run through it)
N1 - Cult of the Reptile God (Great plot, great mystery, but it usually falls apart when the party doesn't catch on to the mystery and just decides to stay the night at the Inn)
S1 - Tomb of Horrors ("Fun" for the DM, not for the players)
XL1 - Quest for the Heartstone (using the premade characters - Strongheart, Warduke, etc. - wasn't as fun as I thought it would be, the adventure is overall serviceable but mediocre. The climatic battle sucks and is cliche)
Labyrinth of Madness (2E) (This reads like a powered up Tomb of Horrors, but has so much backtracking it gets old quick)
DL1 - Dragons of Flame (The start of this epic storyline is a bit too directionless and easy for the party to shrug and ask what they need to do/where to go next)
RM1 - Roots of Evil (The players quit after the opening scene with unavoidable death. It soured me on running any other 2E Ravenloft adventures due to the similar start in. every. one.)
Three Days to Kill (3E Atlas Games) (It has a great story with a deadline, the problem is when the players get to climax the unexpected happens that only the DM will understand and the whole adventure becomes something else entirely)
B4 - The Lost City (In the age it came out, there wasn't a TSR adventure like it and I failed to understand it properly. Plus there is a lot that's only a skeleton for further development by the DM; Like Castle Amber, the OAR version has done this for the DM, and I look forward to running it in the short term future)
N1 - Cult of the Reptile God (Great plot, great mystery, but it usually falls apart when the party doesn't catch on to the mystery and just decides to stay the night at the Inn)
S1 - Tomb of Horrors ("Fun" for the DM, not for the players)
XL1 - Quest for the Heartstone (using the premade characters - Strongheart, Warduke, etc. - wasn't as fun as I thought it would be, the adventure is overall serviceable but mediocre. The climatic battle sucks and is cliche)
Labyrinth of Madness (2E) (This reads like a powered up Tomb of Horrors, but has so much backtracking it gets old quick)
DL1 - Dragons of Flame (The start of this epic storyline is a bit too directionless and easy for the party to shrug and ask what they need to do/where to go next)
RM1 - Roots of Evil (The players quit after the opening scene with unavoidable death. It soured me on running any other 2E Ravenloft adventures due to the similar start in. every. one.)
Three Days to Kill (3E Atlas Games) (It has a great story with a deadline, the problem is when the players get to climax the unexpected happens that only the DM will understand and the whole adventure becomes something else entirely)
B4 - The Lost City (In the age it came out, there wasn't a TSR adventure like it and I failed to understand it properly. Plus there is a lot that's only a skeleton for further development by the DM; Like Castle Amber, the OAR version has done this for the DM, and I look forward to running it in the short term future)
And some are just stinkers
B8 - Journey to the Rock (3 paths and your choice is blind with no hint what's down each way. Only one of the paths is the "real" one).
WG7 - Castle Greyhawk (It's a parody full of puns and nothing I'd ever consider seriously running)
H4 - Throne of Bloodstone ("for up to level 100" at a time when TSR had no understanding of how to make a proper adventure over 15th level)
H1 - Keep on the Shadowfell (4E) (It's just poorly designed)
Lights of Xaryxis (It tries to be Flash Gordon/Guardian of the Galaxy II/Thor Ragnarok and just comes across as cheesy)
Descent into Avernus (Fury Road is great, but not as a D&D adventure set in Hell)
Expedition to Castle Ravenloft (It makes mincemeat of a classic and tries to turn it from Gothic horror into a Lovecraft Horror)
WG7 - Castle Greyhawk (It's a parody full of puns and nothing I'd ever consider seriously running)
H4 - Throne of Bloodstone ("for up to level 100" at a time when TSR had no understanding of how to make a proper adventure over 15th level)
H1 - Keep on the Shadowfell (4E) (It's just poorly designed)
Lights of Xaryxis (It tries to be Flash Gordon/Guardian of the Galaxy II/Thor Ragnarok and just comes across as cheesy)
Descent into Avernus (Fury Road is great, but not as a D&D adventure set in Hell)
Expedition to Castle Ravenloft (It makes mincemeat of a classic and tries to turn it from Gothic horror into a Lovecraft Horror)