When you control for people sticking to a diet long term, WW has been historically proven as being the most effective weight loss and maintenance diet around. (Of course, SB hasn't been around near as long, so it may just be a matter of time before that title changes hands.)
The thing that I love about WW is that you have a support group and a weigh in on a weekly basis.
You also are encouraged to write down everything you eat, so at the end of the week if you went up or down you can review what went wrong and make corrections from there.
Also WW has the group leaders that are available to sit down with you, review your meals and make suggestions to improve them. At the meetings, the members can share recipes, tips, tricks, and road bumps. It is like this forum here, only in real time. And SB doesn't technically have the forum available to everyone. You have to 1) have internet access, and 2) be lucky enough to find this forum or be sent to it. It is not built into the program like it is in WW.
WW also encourages exercise by giving a points value to your exercise. And as an added bonus, WW gives you prizes whenever you hit one of their mini-goals. (10% of your begining weight lost, every 5 lbs you get a star, attendence for 16 weeks.) This incentive helps you recognize your own success and celebrate it as well.
A part of Weight Watchers that is not recognized by the critics of the diet is that it has its own set of "Good Health Guidelines." For those of you who think that WW promotes poor eating habits, here are the GHG that people on weight watchers are
supposed to be following:
1)Eat at least 5 servings of vegetables and fruit each day.
2)Choose whole grain food whenever possible.
3)Include two servings of milk products (low fat [1%] or fat-free) each day.
4)Have some healthy oils (olive, canola, sunflower, safflower, flaxseed) each day.
5)Ensure that you are getting enough protein by choosing
at least two servings of meat each day. (Includes, poultry, fish, eggs, dried beans, or soy products)
6)Limit added sugar and alcohol.
7)Drink at least 6 glasses of water each day.

Take a multiple vitamin-mineral supplement each day.
It is not a
bad system. People who fail at it either aren't following it correctly, not using the GHG, or they just need a different type of diet for their particular body to respond.
SB, however, does not charge you $9 - $15 per week to follow basic good health. SB also teaches you HOW to eat, where as WW pretty much tells you HOW MUCH to eat. Both diets have their benefits.