Nicklaus, and it's not close. His playing career, his instructional books and videos, and his architecture have had a bigger impact than Crenshaw. Granted, we as a group may prefer Crenshaw's courses, but that doesn't outweigh the contributions that Nicklaus has made to the game.
For the record, and I don’t care what others may say, I like most of the Nicklaus courses that I've played.