We all have our favorite books and it is no secret that mine is J.R.R. Tolkien's The Lord of the Rings, yet what happens when one finds a book that is clearly in the same league even is it is not one's favorite? Take J.K. Rowling's Harry Potter series, for example: it is very different from LOTR yet is still similar in many ways and, while Rowling did not found the modern Fantasy genre as Tolkien did, Harry Potter was an undeniable literary classic that inspired another whole generation of readers and began the Golden Age of Fantasy. All of which is why I call Rowling the the Heir of Tolkien.
That being the case, though, what do I do? Do I call Harry Potter my second favorite book? I could, given my above praise of her, but would it really be true. Sure I love Harry, Ron, and Hermione, yet, emotionally, I am no less attached and invested in the tales of Lyra Silvertongue and Will Parry, Eragon and Sapphira, Sabriel and Lirael, and Will Treaty & Halt; from the His Dark Materials trilogy by Sir Philip Pullman, The Inheritance Cycle by Christopher Paolini, The Abhorsen Series by Garth Nix, and The Ranger’s Apprentice Series by John Flanagan. I love those books (and several others) just as much as Harry Potter, yet at the same time recognize that they are not quite in the same league as Tolkien and Rowling. Close to, but not quite.
Thus, in reaction to this, my Dad and I gradually created what we call Fantasy Book Tiers to measure both a Fantasy author's skill as well as story. Below I will try to articulate what each tier means along with adding a few authors Dad and I agree belong in that rank, but it is difficult to do as authors of the same tier often write quite dissimilar books.
1st Tier: Those Fantasy Masters who break beyond the ordinary conventions of the genre, possessing a unique skill and writing style that regularly shocks and delights even veterans of the Fantastic. (Tolkien ranks as the highest of this Tier for obvious quality reasons as well as the fact that none of the rest would have existed without him.)
Authors: J.R.R. Tolkien, Diana Wynne Jones, J.K. Rowling, Patricia A. McKillip, and The Neverending Story by Michael Ende.
2nd Tier: Books such as I mentioned above, acknowledged classics possessing both story and characters you love, but are not quite in the same league (or tier) as those such as Tolkien, Jones, and Rowling. However, like the Top Tiers, these are crossover books that can be enjoyed and young and old alike.
Examples: The Inheritance Cycle by Christopher Paolini, The Abhorsen Series by Garth Nix, and The Ranger’s Apprentice Series by John Flanagan, The Earthsea Cycle by Ursula K. Le Guin, The Bartimaeus Sequence by Jonathan Stroud, The Dark is Rising Sequence by Susan Copper, The Noble Warriors by William Nicholson, and His Dark Materials trilogy by Sir Philip Pullman.
3rd Tier: Good page-turning books that leave you genuinely caring about the characters and awaiting sequels, yet are not what you would recommend to a friend trying to get into Fantasy. Average one might call them, though I think that term a tad harsh.
Examples: The Children of the Lamp series by P.B. Kerr, The Annals of Drakis by Tracy Hickman, The Chronicles of Prydain by Lloyd Alexander, and The Echorium Sequence by Katherine Roberts.
Here ends the tiers, as Dad and I use the term "4th Tier" to describe books we deem unworthy of our time. (After all, why read a lesser book when you could be searching for undiscovered better ones or re-reading classics?) More to the point, these rankings are not ironclad for the simple reason that every book is different and may be of varying quality even if they rest in the same tier. Dad and I, for example, describe The Dark is Rising and His Dark Materials as "upper 2nd Tier" as we judge them as good as it is possible to get without being Top Tier. Furthermore, Dad and I have been debating whether The Children of the Lamp is "upper 3rd Tier" or "lower 2nd Tier" for years. Hence these Fantasy Book Tiers are merely approximate categories we created to sort our favorite books into a more organized literary canon.