I would say that they are mostly all very good. What are you looking to get out of a posing book. They all have the same advice and rules and guidelines, but the bottom line is that posing is dynamic. It's all comes down to the ability to look a a scene and see if it looks good or looks bad. Posing books just help you know where to start changing to make it look better. Books help with basics, but it doesn't start feeling any different until you start posing real people a lot of times. Eventually it starts feeling less awkward. That's what I found at least, although it still feels pretty awkward.