Weight Watchers worked well for me till they were constantly tinkering with the program. Just as I'd get used to one program, it would be revised, I'd go off the rails and up went the scale. i understand that the program has to change as new research comes out, but WW was getting ridiculous and expensive.
Still, WW is a sound, healthy program, not a fad, and I would recommend it at least to start.
What I don't like are programs that restrict what you can eat. A friend is on some version of the Paleo diet. The foods she cannot eat are ridiculous. Tomatoes? Unless a person can't tolerate the acidity, tomatoes are very healthy -- Vitamins A and C. I can see ridding yourself of junk and unhealthy carbs, but I don't see the point of restricting food that is good for you. And I'm not sure Paleo teaches portion control. Weight loss is not just about what you eat, but how much you eat.