1. David Gemmell
2. GRRM (and this is based on only reading aGoT!!!)
3. Stephen King
4. James Barclay (and this is based on only reading Dawnthief)
5. Robert E Howard (Conan, come on)
Gemmell is listed first because I own every book he has written. He is the master of writing about charaters who walk the grey line, not your average heroes. My other choices are fairly weak as I tend to read horror and mainstream more than fantasy, although Gemmell is by far my fave author.
GRR Martin has grabbed me hence his high ranking, as has Barclay. I fully intend to read everything these gentlemen have produced.
King is a multi-genre master, he is a story weaver and a master of the craft.
REH writes absolute cliche-filled brainless twaddle... And I love it.
Just bumped out of my list is Salvatore and I wasn't sure if I could include people like Anne Rice, Michael Crichton, Matthew Reilly so left them out.