A'tuin
Villager
I have to concur, at least in theory, due to the sustained popularity of the adventure since its first release. Even back in the day, I don't remember B2 being nearly as popular as G1-G3 (The Giants series). Furthermore, of the B-series, I think B3, The Palace of the Silver Princess must have been more popular than B2. Certainly, C1, The Hidden Shrine of Tamoachan was played much more than B2. So, in my opinion, B2 wouldn't even be on the radar in terms of sheer numbers if that is what you are going for. So, I'd say, if not 5e Phandelver then it has to be Ravenloft (in general), so long as we are considering the Curse of Strahd as equivalent to Ravenloft. While it is routinely considered the best of the 5e campaign adventures, Curse of Strahd pales to a proper campaign integration of the original adventure, I6, Ravenloft.Ravenloft is my guess. It has a version in at least four editions of the game.