I'm not sure I can really answer this the way it's set up. I don't read much science fiction. My favourite author overall is Neil Gaiman, for the way he paints fairy tales and dreams with deceptively simple words that reach out to the ancestral root of myths inside us.

But overall I have a classification system for my authors. I have A-List authors, whose works I purchase as soon as they are released, in hardcover if that's how they're published, and then I have B-List authors, whose works I collect over time, often in paperback and years after they're published. Then there's everyone else, some of whom I like, some of whom I don't, some of whom I haven't read.

At any rate, my current A-List is, in no particular order: Neil Gaiman, Brandon Sanderson, Matthew Stover, Patrick Rothfuss, Scott Lynch, George Martin.

My current B-List is: Guy Gavriel Kay, Robin Hobb, Tad Williams, Stephen King, R. Scott Bakker, Steven Erikson, Jim Butcher, J.K. Rowling, Gene Wolfe, Dan Simmons. EDIT - Neal Stephenson and China Mieville fit here as well.