I remember reading a thread asking the same question some months ago. Many people were saying Middle Earth from LOTR trilogy, and I agree with that, but since I have just watced FotR, I will take it one step further and vote for Lothlorien, the forest of the elves in FotR. Its beauty, lighting, peace, and mysticism, with that slight touch of eerieness, makes it special for me.
I don't think any other fantasy world has left me so awed.
I loved the world in the movie Dark Crystal. Everything about it was beautiful, and so well designed.
"The world is indeed comic, but the joke is on mankind" ~H.P. Lovecraft
You can't compete with Tolkien when it come to single-handedly crafting an epic fantasy world complete with history & mythology.
However, 'The Old World' created by Games Workshop for their Warhammer Fantasy Roleplaying Game is arguably equally impressive.
I also enjoyed Conan's Hyperboria, Dragonlance's Krynn and Earthsea - the setting for Le Guinn's books about the wizard Ged.
Oz. I would like to defend myself against Tolkiens when saying the only reason Middle Earth doesn't qualify with me is only because I haven't read the books nor seen the films (I won't either UNLESS someone convinces me that they have enough plot for the movie running time). The others that are worth mentioning are The Marvel Universe, Hellboy, Skulduggery Pleasant, the Watch Universe(Night Watch), Assassin's Creed, Vampire Hunter D, Lost Girl and finally the Angelverse. The singular films of fantasy that are worth watching are Dark City and Jade Warrior.
"If you don't like your ideas, stop having them!"
As I said, the only reason that Middle Earth is NOT included on my list is because I haven't seen a LOTR movie nor read a LOTR book.
"If you don't like your ideas, stop having them!"
Lothlorien and the worlds of Middle Earth are great but ...
The Grid, from Tron: Legacy has to be my new favourite world.
Watched the movie recently and felt as if it was like stuff from a dream, everything was just spectacular!
I'm also a big fan of the Kingdom Hearts games, so if they ever got done into movies then I suppose I could choose a few of those worlds.
I agree with you about Middle-Earth. I would also like to mention the world depicted in Stardust. I'm not sure where they filmed that movie at but it looks great!
Never rub another man's rhubarb.
Middle Earth
Hogwarts (Best fantasy school ever :)