Is one of my favourites, and I regret getting rid of it when we purged all our 3rd edition D&D books a while ago, but I also quite liked the more in depth books diving into certain areas, have very fond memories of the Serpent Kingdoms, plus the likes of Silver Marches, Magic of Faerun, Lords of Darkness - and while I understand why WOTC doesn't produce these types of books anymore, I do wish they did.Erm no the 3.0 FRCS is quite well regarded.
Ah well, am planning to get the PDF versions of these books off DMSGuild at least.