Here's my two cents, for what it's worth.
I think any diet you can stick to will work, though some are faster than others. However, if you are currently on Atkins, it may be a difficult change. Atkins is meant to be a lifestyle change and when you bring carbs back into your diet there can be repercussions, ie. gaining weight back.
So if you think that weight watchers will be better for you to sustain similar eating habits in the future then change, but you could go up before you start going back down. However if you have found atkins to be something you can adapt but keep long term then I wouldn't switch. Hope this helps.
“Life is a bowl of cherries. Some cherries are rotten while others are good; its your job to throw out the rotten ones and forget about them while you enjoy eating the ones that are good! There are two kinds of people: those who choose to throw out the good cherries and wallow in all the rotten ones, and those who choose to throw out all the rotten ones and savor all the good ones.”
― C. JoyBell C.