Voted Home Brew
I run a highly modified Greyhawk campaign. Well, I kept the map and a few of the names, anyway. I borrow from everything and anything. I've used material from the EQ Tabletop RPG, Warcraft, Scarred Lands, Dragonlance, Kalamar, Midnight, and several more. About the only one I don't use is Forgotten Realms.
IMO, Forgotten Realms, while undeniably popular, is one of the hardest settings to have fun adventuring in. I say this because I always feel like there is no "new" ground to cover. The big name characters have already been there, done that. If I throw out all of the history and just use the maps, as I have done with Greyhawk, there is really no point to running the rest of the FR line. I love some of the Forgotten Realms books, but I don't think the world is really supportive of adventuring. WotC could just as easily invest the time and resources into creating a new world.
Eberron, unfortunately, with it's outrageously high level of magic, disappoints as well. Why can't WotC publish a world with lots of room to adventure, moderate magic levels, and let the DM decide on history, politics, etc? The Greyhawk Gazeteer is great this way. I think Greyhawk is a lot of fun when you ignore the RPGA.
I think the formula for a good setting would be a well-defined map, lots of support (Like Races of Faerun) and modules that a DM can decide to use if necessary. Hence I like home brew. It's good to borrow at will from other settings.
It's just my opinion, though.