Here's a dividing line for ya:
Within 1e, you see the classics of the genre:
1977 Monster Manual
1978 Player's Handbook <=--- all the player stuff in one book
1979 DM's Guide
1980 Deities & Demigods
1981 Fiend Folio
1983 Monster Manual II
1985 Legends & Lore
Above this line, everything is universal, not setting-specific , no power inflation, no player-facing stuff outside the PH
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Below it, setting-specific or whacktastic new player-options - or, as in OA, the vanguard, /both/
1985 Oriental Adventures <=---- setting-specific with player stuff: more classes, weapons, spells and other craziness, but better & with Ki powers! Sets the tenor for the whole trainwreck.
1985 Unearthed Arcana <=--- more classes, weapons & spells and other craziness, with whacked balance, even by 1e standards
1986 Dungeoneer's Survival Guide <=---- more player-facing options
1986 Wilderness Survival Guide <=---- more player-facing options
1987 Manual of the Planes -----===> may be stretching the point to call the planes setting-specific
1987 Dragonlance Adventures <==--- setting specific
1988 Greyhawk Adventures <==--- setting specific