Books mentioned (including the top ten, the honorable mentions, series I want to read, and the unfinished series -- alphabetized by author):

Joe Abercrombie's First Law
R. Scott Bakker's The Second Apocalypse
Jim Butcher's The Dresden Files
Susanna Clarke's Jonathan Strange and Mr. Norrell
Steven Erikson's The Malazan Book of the Fallen
Steven Erikson's Kharkanas Trilogy
Ian Esslemont's Path to Ascendancy
Ian Esslemont's Novels of the Malazan Empire
Neil Gaiman's American Gods
Lev Grossman's The Magians Trilogy
John Gwynne's The Faithful and the Fallen
Robin Hobb's The Realm of the Elderlings
N.K. Jemisin's The Broken Earth Trilogy
Robert Jordan's Wheel of Time
Stephen King's The Dark Tower
R.F. Kuang's The Poppy War Trilogy
Mark Lawrence's Broken Empire Trilogy
Ursula Le Guin's Earthsea series
Scott Lynch's Gentleman Bastard Sequence
George R.R. Martin's A Song of Ice and Fire
Terry Pratchett's Discworld series
Patrick Rothfuss' The Name of the Wind
Brandon Sanderson's The Stormlight Archive
J.R.R. Tolkien's The Lord of the Rings
Tad Williams' Memory, Sorrow, and Thorn
Gene Wolfe's Book of the New Sun