Heinlein:

Best known and most influential on society at large: Stranger in a Strange Land.

Best political and social thought (in my opinion): The Moon is a Harsh Mistress.

Most fun read (in my opinion): Glory Road.

Most influence on me personally: Between Planets (first of his juvies I read at 10 or 11, one of the major causes of my being hooked on sci-fi for the following nigh fifty years)

Best novel: Give me a break! Anyone who can claims he can call that one, I want some of what he's snorting.

Peter.