You yourself can decide which one works best for you. Even if you have not bought either of the books, ultimately, just by researching BTG forum, you can see what are the techniques that the two books offer.

The bible is the best resource. But, that is based upon my experience and comfort with the technique they provided. I used to get CR questions wrong while trying to just look at the question type, but ever since I started focusing on the actual argument, my score jumped. The opposite has happened with a friend of mine.

So again, try both techniques without, whatever works for you, stick with it! Stick with it is the best advice I can give you.

Hope that helps.