I have to say that the author I discovered and loved the most is Cornelia Funke. I absolutely fell in love with her Inkheart trilogy and cannot wait for the third book to come out.
The most disappointing find out of all the books I read was David Almond. All of his books were so focused on death and darkness that they depressed me. I cannot imagine assigning any of those books to young adults.
Books Added after the Beginning of the Challenge