Council of Wyrms (Player) - Played when it was first released for a few games. It was fun in a novelty kind of way, but not something we ever played again.
Dragonlance (Player) - For a friend's campaign who adored the setting (I never much cared for it beyond the War of the Lance novels).
Forgotten Realms (Player & DM) - I run all my games in the Realms in various regions (Sword Coast, Amn, Tethyr, The Great Dale, Cormyr, Moonsea area, Western Heartlands, Vilhon Reach are the areas I've used repeatedly in Faerun, with brief sojourns to other areas).
Forgotten Realms: Kara Tur (Player & DM) - Mostly DM, we've played a LOT in Kara Tur (as local characters or Faerunian travellers or mix of both). Would love to see a storyline set there (along with some player options)...would be the first storyline product I'd buy from WotC...but none of us are holding our breath, especially after the recent furor over OA.
Greyhawk (Player) - Detest this setting, but it was the first setting I played in when I first started playing D&D. Didn't hate it when I started playing, but over time I came to find it so utterly boring compared to all the other settings available (once I started DM'ing around the mid 90's).