Hmmm. L.E. Modesitt Jr. is definitely prolific although not entirely for me.

I wonder if you'd like Orson Scott-Cards work, if you haven't read it. Classic speculative sci-fi, and very thoughtful.
There's also always George R R Martin, but I personally feel that he likes killing characters just to annoy readers rather than for any really character-driven purpose (unlike Robin Hobb)