Yeah, this is a common problem in genre fiction unfortunately. The best one I've read is "The Magicians" series by Lev Grossman. The writing is clean, concise, everything is shown and nothing told. The series is a great deconstruction of a lot of classic YA fantasy tropes and has a solid magic system. Can't recommend this series highly enough, both my literary and scifi/fantasy fan friends have all really enjoyed it.
I'd also recommend Ishiguro's The Buried Giant, very close to literary fiction.
It steps a little outside of the bounds of what we think of as "fantasy", but the magical realism genre has a lot of amazing pieces, and the genre is based around fantastical elements. My favorite example of this is "One Hundred Years of Solitude" by Gabriel García Márquez. "Invisible Cities" by Italo Calvino is another good one.
I loved "Remains of the Day" and "Never Let Me Go", but didn't finish "The Buried Giant." The first two aren't fantasy, but IMHO they're much better Ishiguro.
As for "literature-y" fantasy, I'd agree with others here to look at magical realism, e.g. "One Hundred Years of Solitude." But my opinion is probably crap -- some of my fantasy favorites are Tolkien's "Silmarillion" and "Lost Tales," which probably don't qualify as "great literature," but show some amazingly thorough and vivid world-building.
Pratchett was a genius when it came to knowing just the right phrase to conjure up an image, although reading all the Discworld novels in one go as I am at the moment reveals he's not quite so good at the storytelling side, often dragging on a few chapters too long.
Are there any, may lesser known, fantasy that is more literary?