You've definitely hit he nail on the head...lifestyle choices are what's going to give you lasting success. Before you decide on which program you may chose, think about this...
In order for any of these programs to have a lasting affect, you'll need to follow them as a lifestyle to keep the results. If you're not willing to stay on NutriSystem, Jenny Craig or Weight Watchers for the duration, you're likely going to gain all the weight back, and then some...unless of course you're willing to make some behavior/lifestyle changes along the way.
Bottom line, it's not the program that's the issue, it's your relationship with food. And if you're anything like me, I exercise and for the most part eat well...but unless I exercise serious restriction, I can gain weight very easily.
Here's what I've found to be true...we're going to eat...and it's all about moderation. I've found a great program that allows me to eat and safely lose weight without deprivation or major changes in my behavior. I don't know if it will be for you or not, but you can private message me to learn more about it.
My best...if you chose any commercial program, it will work...but be prepared for the weight to come back if you don't change your relationship with food.
My Best,
C.