It also depends on your personality. One of my daughters, together with my sister, joined WWs....then they photocopied all their stuff and I did it with them without the meetings and I did fine...but then I lost all motivation and have since gained most of it back.
However my daughter found WWs made her very angry! She felt like WWs was telling her what to do, and she didn't like it. She is now a FitDay Member and she loves it. Her reasoning is that with FitDay it shows her what she IS doing, and she can decide for herself. I realize it is kind of silly, but that was her mindset.