Like most of you here, I enjoyed the "canon": Tolkien, Leiber, Lewis, Moorcock, Howard, Lovecraft, Burroughs, Cherryh, LeGuin, Herbert, etc. (too many to mention).
In the fantasy genre, I have to admit I burnt out quickly long ago. Pop-fantasy authors seem to have a tough time breaking the mold and either creating a unique story or telling an old story uniquely. Some have even blatantly admitted that they were trying to write a story that was, say, Tolkienesque right down to the race, character and storyline archetypes

. Worst of all sinners (IMHO), is Terry Brooks'
Sword of Shannara. Yes, yes, I know he went on the write better stuff and has become a mainstay of the genre, but I just can't quite forgive him for that first miserable tome. I also make it my personal policy to avoid any book that refers to dragons anywhere in the title or has a dragon depicted on the cover.
Eregon comes to mind (retch).
I don't mean to diss anyone's favorite author; it's just my take on things. I heartily enjoy reading, but get tired of having drivel propagated via pop-culture when there are really richer pickings out there should anyone take the time to dig. Unfortunately most want to be served rather than serve and thus Christopher Paolini has yet another movie coming out based on his second book to serve-up and stupefy the young reader crowd into believing his ho-hum betcha-I-can-guess-what's-gonna-happen-next storylines are "...so good".
A few notable exceptions come to mind, however (Again, MHO only). I really enjoyed Steven Burst's work in the
Vlad Taltos series:
Jhereg,
Yendi,
Teckla,
Taltos, etc. The humor in these always made me chuckle. His
Pheonix Guard series was fun too; an "old story told uniquely".
Patricia A. McKillip's
Riddle Master series:
The Riddle Master of Hed,
Heir of Sea and Fire and
Harpist in the Wind, were a whole lot of fun.
Roger Zelanzny's
Amber series really helped me out with plane-ular travel and the quest mono-myth for my games.
Barbara Hambly's
The Ladies of Mandrigyn series (at least the first two)was great for
believable (I.E. no chain mail bikinis) women warriors.
I also liked Katherine Kurtz'
Deryni novels...at least the first half dozen. They gave me ideas on medieval puzzles and intrigue and politics that were deep enough to employ in game play, but not so deep as to lose players.
The series I have enjoyed the most as of late are Jack Whyte's retelling of the Arthurian legend:
The Camulod Chronicles. Usually I stay away from Arthurian-rehashes, but this one tells the tale from a distinctly pseudo-historical perspective describing how Britian's Roman population tried to keep the light of civilization burning. A unique telling of an old story, it has the feel of Rosemary Sutcliff's
The Sword At Sunset sans the sentimentality for the legend.
Presently I'm reading Simon Scarrow's
Eagle series:
Under the Eagle,
The Eagle's Conquest, etc. I'm enjoying great descriptions of how the Roman army operated during the Britain campaign of Claudius through the eyes of a couple of earthy and interesting characters. I am presently working up a rather grand war in my RP world and these books have given me plenty of ideas.
Some one mentioned the
Thieves World novels earlier. I found another city-centered series with a distinct Middle Eastern flavor by a cadre of authors and edited by Will Shetterly and Emma Bull:
Liavek and
Liavek: The Players of Luck,
Liavek: Wizard’s Row, etc. These have great gaming ideas as well as a great essay in the back of the first anthology explaining the magic and traditions of the city that many a GM would do well to emulate when working up a major city from which they plan their players to launch their heroic endeavors.
And then...LOL...so many books, so little time