Mary Stewart wrote what is, to date, my very favorite King Arthur series. I love the idea of the sword in the stone, the magician, and the round table. I've read dozens of books about King Arthur and Merlin. None of them compare to this set of five books.
The Crystal Cave, The Hollow Hills, The Last Enchantment, The Wicked Day, and The Prince and the Pilgrim were all just wonderful. I gave them rave reviews (and several perfect 10's). They are the one set of books that I gave away that I wish I never had. I will have to replace them one day.
I want to read them again.