Lovecraft or Hesse. I feel saying Hesse since I've only read 3 of his books. I'm certainly qualified to make a judgment about Lovecraft, though, having read at least 90% of his stories (though very little of his poetry and incredibly voluminous correspondences).
Where to began???
My all time favorites are probably JRR Tolkien, Frank Herbert, George RR Martin, and CS Friedman, and Daniel Quinn.
But there's also Terry Pratchett, Douglas Adams, Mercedes Lackey, David Duncan, Bram Stoker, Orson Scott Card, Melanie Rawn, Ray Bradbury, and Madeleine L'Engle.
And more....but I'm not going to put them all