Another thumbs-up for Michael Scott Rohan from me.
And another author: John Crowley - in particular:
Engine Summer: possibly this should be categorised as SF rather than fantasy, but to me at least it has a very 'fantasy' feel. A beautiful description of a young man's journey through a post-apocalyptic America - and also a complex and fascinating puzzle, with assorted hints and clues, for those who like such things. I haven't seen it published on its own, only as part of a collection entitled Three Novels or Otherwise.
Little, Big: this is definitely fantasy, albeit set in a near-future America. It can be read just as a story, but it's marbled with hints and allusions drawing in elements of many myths and legends.