I can't comment on which is the better photographer as I'm trying to get away from that mindset. That said I prefer the work of Brett Weston as you say there is more mystery and I've also had a hidden love for "empty blacks". Sometimes being able to see into the shadows takes away the mystery of what might be there. Saying that I'd be happy to have the work of either on my walls.
I think his underwater nudes are some of the most beautiful I have ever seen.