I don't remember what the first (published) adventure I ever played; my first RPG session was a homebrewed one by my friend (AD&D). The first one I ran was for TOP SECRET, called Sprechenhaltestelle.
B1 in search of the unknown run by my best friend's older brother. they found out i played chainmail and asked me if i'd like to play something a little different. it is still my favorite published adventure. my favorite overall though is the dungeon i ran for 11 years for my group. 3-4 hrs / day ; 5 days / week ; 50 weeks / year. 1 lvl per 900 hrs of roleplaying.