Ben is the guy to see if you ever get the chance to go to a Photoshop Seminar. You will definitely walk away feeling your money was well spent.

As to which is a better author...

Katoran, you need to look at "What do i want to use Photoshop for?" if, as you mentioned in your post, you just want to invest in PS to pump-up your renders so they really kick @$$, than the "fluffy" style books will give you a good starting point. If you hope to expand beyond that and land a job as a graphic artist in a gaming company then you'll want to branch out more into some of the deeper "hands-on" "let's take a peek under the hood and see how this puppy works" style of books.

either way, you can always ask question here ;)

:)
retrocity