I have found Slimming World pretty good. It is more about eating a healthy diet than anything else, but it does cleverly control the calories without you realising. What I like about it is you can eat unlimited fruit, veg and certain dairy products, so never get hungry and fruit/veg and calcium sources aren't limited like some diets.
My problem is, I find making any changes at all difficult to stick to long term. It's easy when my husband is away (forces) but I always feel guilty not making him 'proper' meals when he's here and so end up on the slippery slope again...
So, I have just started trying 'myfitnesspal.com'. I've put the app (free) on my iphone or you can access it online. You tell it how old you are, how much you weigh, what you're target is and how much you want to lose per week and it works out the calories per day you need to eat to aim for that. If you exercise you can 'earn' extra calories, and it works that out too. You keep a food diary and it works out calories eaten and then tells you how many calories you have left. I'm finding it pretty good as it is making me conscious of what I eat, encouraging me to make good food choices so I feel full and making me think about how I exercise too. It is also making me realise just how many calories/rubbish are in things I would eat without thinking it was all that bad, such as the Macdonalds breakfast I wanted the other day, which was 740 calories!!! I genuinely thought it would be about half that!
It's early days, but I'll see how it goes...
Having 2 pregnancies back to back really hasnt done me any favours (weightwise) and I am really struggling with weight now 
