The bulk of my favorites all come from a single issue, Dungeon #45.
An Artist's Errand by Steve Kurtz, Rudwilla's Stew by Chris Perkins, & Prism Keep by Rich Baker.
As a 14-year-old I had no idea who these people were (or would become in Mr. Perkins' case). In reality, it was 30 years later that I went back and realized who was writing the adventures that were in the magazines.
I've ran Rudwilla's Stew as a campaign opener for pretty much every campaign I've ran since 1994. The only issue I've had with it is in the final scene where the players are required to determine who poisoned the stew, it isn't very well described how to run the encounter such that the bugbear shaman is to be identified as the culprit. It requires a decent amount of dramatic exposition to play it out, as it is set up to be a solely role-play experience. I've ran it several times in 5E converting it on the fly as well. It is really well set up for the scene style play of 5E.
Prism Keep really needs a set of pre-gens so that it could be a perfect intro into 2E AD&D. It is a self-contained "dungeon" that doesn't fall into the trap of lots of other similar modules of the era of stripping the characters of their stuff and/or starting them off in a prison. If you've ever wanted to give 2E a go, Prism Keep would be my top recommendation for doing it. It's a mid-high-level adventure with a good mix of puzzles, traps, combat, and negotiation that lets both the DM and players really get the opportunity to flex the system.