Ok there are a million diets, but I have alot of experience with diets, I know which work, and I know how to get people who are even extremely over weight (700+ pounds) fit again.
But for your average person that isn't needed. If you have extra weight, some minor changes in your lifestyle can have you getting more fit, losing weight and feeling healthier...without having to drastically change what you eat, or spend long hours working out etc.
First step, I personally think everyone should take, is cut out all soda. If you must, drink it every so often when eating out (once or twice a week), but that is it. Alot of people struggling with weight drink soda often, even if it's diet you still usually get alot of salt, and it's just plain not healthy. There are tons of drinks that taste just as good as soda, without any sugar (I use Mio's for me and my wife for instance).
The next big deal is to control just how much you eat...especially the carbs. I'm not saying no carbs, but if you have other types of food there as well, you won't need to eat as many carbs to feel full. Salad.....is pretty much amazing for diets, since it's very healthy (as long as your not putting unhealthy dressing on it...itallian dressing (not creamy) or oil and vin are what I use. I have a salad with dinner every night. I use live lettuce because at least where I live it's not much more expensive (2.99 vs 2.50 for a head), and it's fresher and tastier. I have it first before my meal and it keeps me from starvation eating (IE I'm super hungry and eat more then I need).
Another good idea, always try and have some veggie with your meal. If I'm making chicken, steak or fish etc...I make a yummy veggie side dish. There are some great stir fry options (packages with broccili crowns, snap peas, carrot slices etc) in most grocery sections. Two bags of them tossed in my frying pan with a bit of water first (covered) to steam a bit, then a bit of olive oil to fry it...touched off with a few spritzes of terriky sauce to ad a bit of flavor...and you have a great side dish. Just switch out different veggies to keep it fresh (they sell bags of brussle sprouts for instance, or caluflower etc). If you have as much veggies on your dish as everything else your eating...along with a starter salad, you'll find yourself quite full without sacrificing the type of foods you want to eat.
Another idea is to experiment with different dishes. For instance, I used to make a sinful insanely good Lasagna. It was made with noodles, my meat sauce (hamburger meat + itallian sausage), and 3 types of cheese. It was so good everyone would eat till they where stuffed every time. I stopped making it a few years ago because of that (Seriously nobody had the ability to resist the evil lasagna including me).
So awhile ago, I tried switching it up a bit. I got low carb noodles...but that by itself really wouldn't make a big difference. I go with the same sauce I used before (just only a tiny bit of sausage now), but I use half as many noodles and cheese...instead I slice up yellow zuiccini squash and use that as 2 layers in my lasanga...along with slivered carrots as well (which I stir fry in a pan first before adding it in). I have even made vegetarian versions (Without my meat sauce) and while it's not as good, it's still very yummy (probably great if you are actually a vegetarian...but I just did it because I had a friend over who is...usually we go with the meat variety).
Finally, fill your house with healthy snacks. Keep yourself from ever getting to the point where you are starving, and prevent yourself from going for bad foods by having good healthy snacks around instead. No candy, ice cream etc, instead fruit is great to have as snacks. Bannana's and apples (we like fuji the best), have peanuts around if you need some quick protien etc.
That of course is just the food portion...but it's very important. The other portion is actually moving around. It's good to have some form of exersize you do regularly, even if it's just water aroebics. Try and walk if you can (not everyone can at first) instead of driving everywhere. Going to eat then shop nearby? Park where you will shop, then walk to where you are going to eat and back (so you don't have to move your car...and you got some walking in as well!).
Another nice way of moving more, is to not do large shops. Get all your food fresh each day if you can fit it into your schedule. If it's on the way home etc, just run in, get the food for the day, and use the express lane or self serve lane to save time. If your store is like mine, you'll probably end up saving time over all by not having to wait in the long lines (Seriously sometimes it's 45+ minutes to check out with a cart!!).
If you have set your life up in a way that you are happy, that is the best way to lose weight. Focus on food, making yummy food you really enjoy, spend energy and time making it, and you will end up with more energy and you'll end up being happy with the weight loss process.