There's been some talk lately about the horrors of 2nd edition AD&D. Technically, 2e is the version that was on the table when I've played and DMed the most, but the truth is, I've always played Moldvay/Cook with a thin veneer of other rules layered on top. Maybe that's part of the reason why I never made the leap to 3e. You can't just trowel on a few character creation rules and spell lists and have done with it. And that's honestly what I did with every edition of D&D that came into my hands. In that sense 3e and all that followed after it "isn't D&D." But that's a fairly narrow definition of the game, based entirely upon my laziness.
Taking what I did use from 2e, though, it's got one distinction that I miss when I play in other editions. 2e (and here I'm using just the core rules of PHB, DMG, and MM) really got clerics right. The rules for specialty priests make your priest of Zeus play differently than your priest of Thor than your priest of Bast. This was especially true if your DM was, like me, brave enough to create spell lists that didn't include most of the healing spells. With the spheres rules as laid out, it was a fairly simple thing to custom tailor clerics to your campaign. It was a bit of work, but nothing like the effort required to do the same thing from scratch for 1e.
In the end, I decided not to attempt something similar for my Moldvay/Cook/Labyrinth Lord hack. Instead, I've crafted the setting so that universal cleric spells make a bit of sense. But in the future, I can see myself attempting to recreate 2e's clerical spheres, if I don't just make separate classes for every priesthood.