Kelewan and Midkemia (Feist),
Amber (Zelzany), of course
The multiverse of the "Elric of Melniboné" and Hawkmoon series (Michael Moorcock)
The whole Hyperion / Endymion universe, even if it's not really a "fantasy world" (Simmons)
And the Discworld , awesomely crazy (Pratchett) :D
I am a BattleTech Man myself!
Definitely, for me, the world of Malaz (Steven Erikson and Ian Esselmont series of books) is the most impressive, coherent, vibrant and exciting fantasy world ever described. I'm a big fan of Tolkien, but I rate The book of the Fallen even higher. The first step (Gardens of the Moon) may seem difficult, but the reward woth the effort once you've fallen in.
Otherwise, The 7 kingdoms (Iron Throne) is a must and of course Dune. Purists will say it's not "fantasy" but it's an incredible imaginary world.
world of warcraft
All these mentions of Greyhawk, Faerun, and even Dragonlance, but not one reference to the most interesting D&D settings of all: Ebberon and Dark Sun.
I'd have to join the votes for Middle Earth, Westeros and the Warhammer world too.
As far as D&D settings go, I'd say Eberron and Athas (Dark Sun). I do like Paizo's Golarion (Pathfinder) as well. I haven't read a lot of fantasy literature but Middle Earth wins my vote there. Narnia is a close, fantastic, second.
On the science-fiction front, if we can go there, I'd say my favorite are, in order: 1) Herbert's Dune universe, 2) Marc Miller's Traveller (3i or earlier periods), 3) Niven's Known Universe, 4) Asimov's Foundation, 5) Lucas' Star Wars universe, 6) GW's 40k universe.
So. Yeah. I guess I'm more about SF than fantasy. :)
From all the fantasy books I've read, or those I know things about, the top five are, in order:
1) Arda (Lord of the Rings);
2) Westeros (A song of ice and fire);
3) Hyboria (Conan);
4) Eberron (D&D);
I also find pretty interesting the Dark Tower series world, even though it's kind of confusing sometimes - and steampunk, or something near by.
nice to see Athas get some love as i think its one of the most intersting D&D/rpg worlds. the ecologial themes and the dragon-sorcerers make it stand-out against most other D&D worlds.
I'd probably have to choose:
- the worlds of H.P. Lovecraft's Cthulhu mythos (if that counts),
- Jack Vance's Dying Earth
- Frank Herbert's Dune
- Robert E. Howard's Hyboria
- D&D's Planescape and Dark Sun
add them together and (hopefully) you get the type of world i'd create myself ;)
Some of those which are already been mentioned and another one (don"t think it has been mentioned here) that always pleased me : Lankhmar from Fritz Leiber.
Oh, yeah, glad you mentioned Planescape. I hadn't thought of it as a "world" but I guess it should be. It's one of my favorites.