Out of that lot? Favourite is by far the Forgotten Realms Campaign Setting. Made by WotC in it's 3E heyday, seemingly with a lot of love and care, and unmatched by the core books nor anything that followed, IMO.
Runner-ups are Magic of Faerun, because it expands the spell list of the PHB to a point where the spell selection doesn't seem like generic lean pickings, and Monster Manual II, because it undoes some of the damage to the game's atmosphere that the selection in the Monster Manual did. I expect Fiend Folio will help in that department too...