I don't exactly hate any one setting, though some have elements or ideas that don't really appeal to me as a DM nor as a player. Ravenloft comes to mind. The occasional horror themed adventure is one thing, but basing an entire setting around that becomes pretty oppressive as far as themes go. I play D&D to have fun, not to be running ragged just to survive like in some fantasy incarnation of the Resident Evil franchise. That, and it was just never that scary to me; the one thing it tries so hard to be, it isn't.
I'm fairly familiar with Forgotten Realms but mostly because I read a few novels (some good, some bad) and the rest of the time the setting was shoved in my face by the monstrous amount of support it had in 2e and the computer games that followed. To me, FR will always be a setting for hack-n-slash fests (I play Neverwinter Nights on occasion for just that reason). The world just feels thrown together with no real rhyme or reason, as some have already mentioned. Calimshan and Al-Qadim seem redundant together, Mulhorand and Kara-tur are obviously tacked-on additions and just don't jive with the rest of the setting. The pantheon irks me (Oghma is a Celtic god, Tyr is Nordic, it was like Ed was picking and choosing gods from real world mythologies at random), as do the uber NPCs and high magic/power level. Fey'ri rub me the wrong way too (how can we make elves even cooler, I know, let's cross-breed them with demons!). Drow were all but demystified. FR has a lot of detail, yes, but it lacks consistency and cohesion, not to mention originality. I never participated in a FR campaign that lasted for more than a couple of sessions before it folded (though it's partly because of the DMs, I'll admit).
On a side note, I first started gaming with Dragonlance, and while some of the original gaming material for the setting can be embarrassing, it remains one of my favorite settings if only for nostalgia's sake (my first DM was awesome too). Some of the books are good reads (though the original trilogy felt somewhat rushed and inconsistent, Weis and Hickman's later books have been better, the Twins trilogy especially since it concentrated on a select few characters rather than an entire party). The 5th Age kind of ruined the setting for me, and I haven't caught up with the latests books either (I only read the first 2 of the trilogy concerning the return of the gods). But I agree that DL is a better setting to read about than to play in what with the abnormally high number of world-shattering events, that and kender PCs really annoy me (though reading about their antics is another matter entirely).
Spelljammer I have a soft spot for since I gamed in a few adventures with some pretty far out ideas from that setting. That and I really like the later offerings in the Wizardry series of computer games, which featured sci-fi elements like spaceships and even a race of militaristic firearm-toting rhino men. I liked the setting because it was odd.
Planescape I'm somewhat iffy about. A lot of the ideas I like; plane hopping has a lot of potential for adventures and something I want to explore more with my custom setting. As for Tony's art, I rather liked it since it reminded me of Amano's ethereal style of art from Final Fantasy fame. But the pervasive cant was a real turn off (berk this, barmy that). If I want smarmy in-your-face attitude and nearly unintelligible cockney slang for dialogue, I'll watch a Guy Ritchie movie, thanks. The demystifying of gods and planar powers is also something I want to distance myself from. Plane hopping should be a high level affair, which is inconsistent with much of PS, but just about right for my game as it approaches levels 12-15.
.
