Quickleaf
Legend
AD&D, for sure. I really like Elminster's Ecologies for the way those books paint word pictures (and encounter tables) of both specific areas of the Realms, but those specific areas can also be extrapolated to similar terrain types in a homebrew setting. That sort of lush description and ecology is something I've seen diminished in modern D&D.
But it also depends on the topic.
For example, if you're delving into lore on Sahuagin, Illithids, or Beholders, then nothing compares to corresponding AD&D Monstrous Arcana books. And AD&D Giantcraft is a good one too.
If you're interested in ancient lore about proto-civilizations, the Sarrukh, Jhaamdath, the Tearfall... there are some great sources in 3rd edition. Serpent Kingdoms comes to mind.
Whereas, if you want more recent lore that gets into depth on Cormyr or Westgate, believe it or not 4th edition had some excellent online Dragon magazine articles (#365 and #407).
And even though there's revisionism happening in 5e, the dragon lore they've created in Fizban's Treasury of Dragons is really fascinating, and Volo's Guide to Monsters compares favorably to many AD&D sources (though certain AD&D books like the Illithiad and Eye Tyrant have deeper coverage of mind flayers and beholders).
Whereas if there's a specific monster you want more lore on, I recommend tracking down if it has an "Ecology of" article in Dragon magazine – those articles span AD&D, 3e, and 4e I believe. So if you want, for example, Ecology of the Annis Hag, you need to go to Dragon #345 (published during Paizo's 3e run).
But it also depends on the topic.
For example, if you're delving into lore on Sahuagin, Illithids, or Beholders, then nothing compares to corresponding AD&D Monstrous Arcana books. And AD&D Giantcraft is a good one too.
If you're interested in ancient lore about proto-civilizations, the Sarrukh, Jhaamdath, the Tearfall... there are some great sources in 3rd edition. Serpent Kingdoms comes to mind.
Whereas, if you want more recent lore that gets into depth on Cormyr or Westgate, believe it or not 4th edition had some excellent online Dragon magazine articles (#365 and #407).
And even though there's revisionism happening in 5e, the dragon lore they've created in Fizban's Treasury of Dragons is really fascinating, and Volo's Guide to Monsters compares favorably to many AD&D sources (though certain AD&D books like the Illithiad and Eye Tyrant have deeper coverage of mind flayers and beholders).
Whereas if there's a specific monster you want more lore on, I recommend tracking down if it has an "Ecology of" article in Dragon magazine – those articles span AD&D, 3e, and 4e I believe. So if you want, for example, Ecology of the Annis Hag, you need to go to Dragon #345 (published during Paizo's 3e run).