Nicklaus has said that Hogan and Trevino were the best ballstrikers he ever saw, so they have to be on the list.
Hogan was said to admit in private that Snead had the best swing. He also is quoted as saying Mickey Wright "had the finest golf swing I ever saw". Add those two to the list.
Tiger Woods is on track to break all of the records, so he also has to be on the list.
Mickey Wright likes Cabrera's swing, so he has to be considered.
I've never seen anyone hit it like Sergio: quality of impact, ball flight, ability to work it, power, so I'll throw him on, too.
When I had dinner with Brian a couple years ago, I recall him saying that Nicklaus, from 1959 to 1968 or so, had the best swing ever: incredible power, height and accuracy, and I'm not going to argue with him. Add early Jack to the list.