It's neither.

Hmmm, I just don't know that I can agree here. It's WAY more philosophical than say Star Wars, which at it's heart is (as you term it) is a "hero's quest". I don't think the heavy handed "the reason you act is because you choose to" stuff was simply tacked on to fill out the movie or as "baggage". I think it was a major reason for the creation of the movie in the first place. I could be wrong about this, of course, but I don't see the creators sitting around going "here's a cool story" and running with it. I think more likely it was, "here is a way that we can present XYZ philosophy and make people think." Of course the brothers won't say, but it really had the feel of a movie trying to make a point.

Also, as I pointed out earlier, it did seem that they changed ships mid-stream philosophically (from faith to choice), which if they had planned from the outset only points to a philosophical film. Of course, I could be wrong and they might have just thrown all of it in the mix trying to make a "thinking man's" movie.