If there was any such thing as a "best" frequent flyer program, one of two things would happen:

a. It would enable the airline that had it to take lots of business away from its competitors. They would catch on and match it.

b. The airline that had it would realize that it was giving away more than its competitors but not taking lots of business away from them. It would cut back its program to match theirs.

Either way, it wouldn't be "best" any more.

There is, however, such as thing as the best program for a specific individual with specific travel patterns and award goals. You'd have to say more about yours for us to offer any meaningful advice.

As for those ads you see: They're often legit, but I have yet to see one offer any information you can't get here for free. You just may have to spend some time here reading threads on a variety of topics to find it.