Part of WotC discovery in building 5E, IIRC, is that DMs are overwhelmingly the ones who buy all the books, even the PHB. 5E books are designed for DMs.Settings are a tool for GMs, not players.
Bingo bongo, number 3 by a country mile...How about we look at the discussion from a different perspective....
Which of the following books would, by itself, allow a GM to run a Chult based adventure not featuring the Death Curse with the least amount of effort?
1. The 3e FRCS
2. The 5e SCAG
3. Tomb of Annihilation