Hm. Two D&D Campaign Worlds spring instantly to mind:
DARK SUN: Because I love games where I can give the Players next to nothing, and they love me for it. I also love games where "Take down the corrupt templar" becomes a suitable goal, as opposed to "Stop evil dragons from invading the world and destroying everything". I like smaller, more human stories, and Dark Sun is a great place to do that - amidst a crazy backdrop. It's also the only D&D setting I can think of (except for maybe Eberron) where the use and existence of magic within the setting actually makes sense.
JAKANDOR: Warriors versus Wizards. Humans only. An actual explanation for why the ruins exist, and why you want to explore them. A setting with few magical items (one whole side destroys such items upon finding them). Neither side is "good" or "evil" - you could have the players vote at campaign start which side they wanted to play. About the only stupid thing in the entire setting were those giant "mech" thingees, and that's more a personal preference. Also, the character kits were really evocative while still allowing two members of the same kit to be entirely different from one another.
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Those are my two settings of choice. I only like Eberron if it's infused with elements of modern history and all the apostrophes in names are dropped. The Realms stopped being good at around the time Nirvana became a band. Dragonlance has never "done it" for me. Greyhawk is too vanilla. Planescape is too weird. Al-Qadim is too swashbuckly. Spelljammer is intriguing, but I must reserve judgement.
Oh, and I'd jump on a Council of Wyrms game in a heartbeat. The one time I played it, I was a silver dragon named Freddie Mercury, and it was AWESOME. Next time, I want to be a copper dragon named Penelope, but everyone can just call her "Penny".