Browse through the "text" of any of these mags (if you can actually unearth it, amidst the volumes of ad pages) and think about what's stated (workout routines, diet plans, etc.). Then flip through the entire mag from cover to cover, checking out the ads and their fantastic claims. You'll probably conclude that each of these is about the same when it comes to truthful, sensibe, factual or insightful information.
I used to love reading these mags. The only time I buy them now is when I have a long plane ride...