Birthright 18
Blackmoor 22
Council of Wyrms 18
Dark Sun 21
Dragon Fist 10
Dragonlance 18
Eberron 25
Ghostwalk 20
Greyhawk 25
Jakandor 21
Kingdoms of Kalamar 20
Lankhmar 22
Mahasarpa 18
Mystara 24
Points of Light (Nentir Vale) 10
Pelinore 20
Planescape 19
Ravenloft 18
Spelljammer 19
Thunder Rift 18
Wilderlands of High Fantasy 20
I currently am running a Mystara campaign. The players seemed to really like that they were playing in a fleshed out game world that was an integral part of D&D history while ALSO not being a world they had ever heard of. It was old but new to them.
As for Ravenloft, I like Tracey Hickman. His books are enjoyable, most of his adventures are fun, and he's a nice guy. But I really never took to Ravenloft. I just don't like vampires, I guess.