OK, is it bad that I've tried almost every diet plan that you mentioned up there? I've seriously tried almost every diet plan in existence (it seems like), and over the years I've lost and gained a total of almost 500 pounds.
In the end though, do you know what did it? I just finally went to a nutritionist and worked out a personal weight loss diet program that was based on two things: moderation, and planned rewards.
I'm not one of those people that can just cut out sweet things, or carbs, or whatever forever. I've tried; it really just doesn't work.
However, with this plan, I've got the rewards all planned out, so I know when I have the caloric budget to accept the sweets, and when its better to wait a while.
Of course, I do slip up, but this has been the best diet plan that I've ever been on so far, and it's starting to look like it really could be a permanent change. My point is, if you really want to lose weight, see a dietitian or nutritionist. Don't do what I did and try to fight it yourself for years, just frustrating yourself again and again.
You really can do it, you really can lose weight (If I can anyone can!), but give yourself the help you need to succeed, don't try to go it alone.
Best of luck!