My absolute favorite book is The Ruins of Ambrai by Melanie Rawn and the sequel is a close second, The Mageborn Traitor. The Exiles series (those two and the third yet-to-be-released) is the first and only series I've read where a matriarchal society was done right. Anytime I read about matriarchal societies, they're presented as the Amazon stereotype. Women aren't men, plain and simple and that's cool. We have all sorts of strengths that could enable us to lead a society and Melanie Rawn uses that in these books.
They also have some of the most alluring characters. Rawn builds beautiful, well-developed characters that you fall in love with, or loathe, but they demand your emotions.

I also really enjoyed the first two or three books in Terry Goodkind's Sword of Truth series. The first of these, Wizard's First Rule was an excellent book that keep me up many nights because I just couldn't put it down. The second was of the same quality and the third was pretty close. However, there are several books after that which were severely lacking in substance.
I had the pleasure of meting Mr. Goodkind at a book signing and was able to talk with him for a bit as I was last in line. When I asked him for tips on writing (as I aspire to be published one day) he told me how it took him his whole life (almost 50 years) to write the first few books and get even one published, but after that, he was putting out close to a book a year because of the demands of his publisher. I credit this for the quality (or lack thereof) in his more recent books.

Another great book is Silverlock by John Myers Myers. It's very original and keeps up a fast pace without losing the reader.