Hey Ann. It all depends on where your head is, I guess. If you're relatively happy with your weight, it's hard to get motivated to stick to any 'diet'.
I would suggest you need to do two things. First, think about your 'last straw' moment - what was it that made you decide you wanted to lose weight in the first place? Second, find a diet that fits in with your lifestyle. If you like to cook and use fresh ingredients and eat three meals a day, then WW Core might be best for you. If you like to eat a wider range of foods and don't mind a bit of weighing and measuring, then WW points.
Slimfast is not for everyone but does suit some people. I would be v hungry on it myself.
There are other diets as well; sometimes it is a case of seeing what suits you - I have done WW before and it didn't suit me at the time, but it does now. Maybe my head wasn't in the right place back then.
Hope this helps.
Karen x