My favorite author of all time is probably Aldous Huxley. His novella 'The Genius and the Goddess' is one of my all-time favorites, but Island is right up there. Otherwise I'd say authors like Steinbeck, Camus, Dostoevsky, Kafka, Sartre and Faulkner all have books in my top ten (and then some).
But for pure reading enjoyment I also am pretty partial to Stephen King, Douglas Preston and Lincoln Child. Pretty big Philip K. Dick fan as well.
I'd say they all have their own influences on my writing - as I'm sure do the hundreds of other authors I've read.