Hello!!!
I also agree that permanent lifestyle changes are the way to go!
A lot of the plans will make you lose weight, but you have to be able to love with them. Honestly, out of the plans that you mentioned, the only one that would be liveable for ME would be Weight Watchers-because in a nutshell, it is a lower calorie diet-the same as calorie counting, which is what I do now-simple eating less and exercise.
I could never live permanently on Atkins-where food groups are cut out completely or extremely limited, or Somersizing, where you have to eat foods in certain combinations only. I just couldn't do it, so I might lose weight, ut eventually I would gain it back because I would end up going off the plan.
For ifestyle changes, use exercise for instance-even if you only start with 10 minutes a day, walking around the block. After it becomes a habit in your life, then slowly increase it to 15 or 20 minutes. Then 30. Slowly change up the routine if you wish-take a class, or add a yoga or strength dvd-anything YOU like to do. (My biggest motto is the best exercise is the exercise that YOU will do!)
Start making small changes in your lifestyle-little by little, so that it becomes part of your life, not part of your "diet".
And visit 3FC for friends who understand, and are here to support each other!