The Book Version or the Movie Version

What do you like best, the movie version of a mystery/thriller or the book version?

I was thinking of the movie versions of books by my favorite authors. Here's some examples:

I love the Easy Rawlins series by Walter Moseley. When Moseley finishes a paragraph you can feel the sub-culture of 1950s LA - I am there! The history is live! So when Devil in a Blue Dress was made into a movie with one of my favorite actors (Denzel Washington), I put it into my VCR with huge anticipation. What a let down! It just couldn't capture it. I wish I could put better words on "it." Is "it" - ambience? flavor? aroma? emotion? stress? I just don't know how Moseley does it but it wasn't in the film. More importantly, I couldn't follow the plot as done on film... and supposedly I already knew it! Nope, the book is better.

I also love Vic Warshawsky, the tough feminist-minded insurance investigator created by Sara Paretsky. I enjoy the realism in the book and the lead character is very believable. The plots are well developed. Extremely fun reads. Then a movie was made with the title "VI Warshawski- Detective in High Heels." My overall impression from the book is that Vic is not exactly a high heels kind of gal-- so right off, you know something is amiss. Then the script plays more like a comic mystery - I assure you that is not the case in the books. The movie was not based on one specific book. As someone on Paretsky's forum states: It "kind of cobbles together some of the stories. It stars Kathleen Turner. It's an ok movie, but doesn't really do justice to Sara's books - a single book made into a movie would be good!" How true.

I could go on, but generally the book is the real deal. Extreme Measures might be an exception. This was a great movie and a great book IMHO.

Here's something I wonder about: Which is more to the point-- ?
(1)People who read a book they like, will spend money to see the movie.OR
(2)People who see a movie they like, will go out and buy the book.