Unpublished Setting: My own (always). I feel I can freely use all the sources which have influenced me (& get it out of my system while working on my writing). I can borrow what I want from Lankhmar, Thieves' World, Greyhawk, Zork, Ultima, LOTR, & everything else that caught my interest.
Published Setting: Lankhmar. Big, BIG fan of the books. Working on a 3E conversion currently, & hope to have my players go on a brief excursion to that realities sometime in the future.
No other setting has grabbed my attention this much; only Greyhawk comes close (that city-state makes me think of Lankhmar, that City of the Black Toga as it is); but, I'd rather play than run that setting, & I seem to be the only player in the group who had any degree of interest in the setting---the Realms has more favor with them.
But, glad to see other people mention Lankhmar.