My least favorite Settings:
-
SpellJammer - My, my, my, do I utterly loathe this setting. Not because of it's ideas (it was, admittedly, a wacky, goofy setting with some interesting ideas), but because of the way the AD&D cosmology was set up, SpellJammer ended up 'infecting' other gaming worlds in which it had no right in. Jammer ships don't belong in Greyhawk, FR, or other worlds, they belong in Spelljammer. Get them out of my other settings.
I remember first reading through my old 2e Monstrous Manual and reading about 'crashed Illithid Jammer ships' and thinking 'What the hell is this? Spaceships in D&D?' That was my first exposure to SJ. If it had existed outside of the giant mess that was the AD&D cosmology, I wouldn't really care as I could easily ignore it, but no.
-
Dragonlance - It bores me as a world, plus it had the dumbest races ever; Gully Dwarves, Tinker Gnomes, and Kender. God, I hate those races.
Other settings that I have problems with (I just feel like ranting):
-
Iron Kingdoms - I've often espoused how downright cool this setting is, but there's one part of it that I have said nothing about; the rules connected to the setting. Privateer Press has great ideas, but I cannot stand the way they handle the rules portion of the game. The rules just feel... clunky and poorly implemented.
-
Planescape - This really has nothing to do with PS, but rather the AD&D cosmology of the Great Wheel. The Great Wheel is fine as it exists, unfortunately, settings that really didn't fit into the Great Wheel were hamfistedly shoved in (Dark Sun? Dragonlance?) when they really should have been separate. Also, in general, the fans irritate me.

-
Midnight/Diamond Throne - I'm just really very tired of hearing about both of them. I'm also sure that some of those people out there who are less than enthused about Eberron (I use the phrase very lightly) are also
very tired of hearing about the new kid on the block.