I'm not a big fan of TSR/WotC settings...
I can say that I like Eberron because it makes sense -- the setting fits all the rules, which is a blessing. Personally, I usually prefer to tailor the rules to the setting, but given the oddities of the D&D rules set, I think this is your best deal. D&D doesn't really map standard fantasy books/movies well, but Eberron is a setting that actually accounts for all the races, classes, psionics, the place of adventurers, etc. For my money it is the best bet.
I also have a general fascination with the Ravenloft setting, at least as a concept, if not its execution. In many ways it worked best as the individual module (one place, set in a standard game world, under a dark and deadly curse) rather than as the Demi-Plane Of Dread, simply because that latter case messes with my head on many levels (If these lords are all cursed, then who are these hapless individuals trapped with them? Why do they share in the lords curse, and in several ways to a much more horrid level? Of are they similacra, in which case, who the heck are the adventurers? Cosmologically, morally, theologically, and mythologically the whole thing unravels.). Having said that, I think the 3e version did the best job of capturing the feeling of dread and horror inherent in the setting, probably because this was handled more by White Wolf (odd with rules, fantastic with setting material) rather than WotC (good on battle mechanics). Ultimately, I think I'd like to find a better set of rules for the setting -- D&D doesn't really match the feeling that well; far too heroic/combative, too much into black-and-white morality, and too little in the way of social interaction rules.
The other settings do little to nothing for me.
Just my 2 cents' worth.