I did well on Weight Watchers till the program changed so often, it became annoying and confusing. and I was not losing. Because I couldn't get to goal, the plan became too expensive. For those who don't know WW, you have to pay every week until you reach goal and maintain for six weeks. You then achieve Lifetime status where you no longer pay unless you gain 2 pounds above goal.
I still follow Weight Watchers basics such as portion control. I have had 2 doctors recommend it, so I believe it is medically sound.
A friend is on Paleo. The good point is that Paleo takes you off processed and junk food. Bad thing is the heavy emphasis on meat (not good for cholesterol) and it restricts some healthy food like tomatoes. The friend has lost some weight on Paleo, but she is missing some of the restricted foods, so she is finding herself "cheating. Not good.