What should I make of all the diets out there?
The problem with most "diet" books is that they don't help you individualize a program to achieve optimal fitness and health. Instead, they are one-size-fits-all books, giving you only recipes to follow, without teaching you the principles. They also make it much too complicated -- getting more fit and healthy is relatively simple. It starts with an understanding that we are all individuals with unique needs.
Keep it simple: eat real food, avoid junk, build your aerobic system.