Dantastic666
I don't think I really need either of these books, but which one is better?
I haven't read either myself. Maybe you should look at the credentials of each author (i.e. where they went to school, how long they've done research if they do research, how many journal publications they've both had within scientific journals if they do publish in scientific journals). Or if you're looking at ease of reading content, maybe look at who has sold more books or who seems more popular.