Rig: Let's not get into a feud of MacDonald versus MacDonald (with nary a Campbell). Ross MacDonald is very good but I don't think he's competitive with John D. They were in different genres.

As for Sci-Fi, Philip K Dick was a major mind-bender and way ahead of his time. In the 60's he was writing intelligently of alternate history, voyages within the mind, and trying to figure out if consciousness could distinguish between states of being. He personified one of my favorite bumper stickers:

"Reality - What a Concept!"