Calorie count. That way, you can have the variety you crave, and unhealthy things in moderation. At first, calorie counting seems like a PITA because you have to keep track of everything, but once you have it down, it is SO much less restrictive and more effective than other methods.
In the end, it comes down to how much you eat vs how much you burn. You can get/stay fat on healthy foods: for me, no other diet plan works because I can overeat ANYTHING. Tell me no carbs, I'll eat 5000 calories of bacon. Put me on a low fat diet, I'll overeat rice cakes.
For calorie counting, all you really need is the internet: you can look up the calories of everything and keep track in a notebook, if you want. I like calorie counting tracking sites: I use Fitday, but others like Sparkpeople, Daily Plate, and a couple others. There are also several smart phone apps if you have a smart phone.
Don't start too low: I like this site
to get an approximate calorie range, and all those sites I listed will also help you. It's tempting to say "If it tells me to eat 1700, I'll eat 1400 and REALLY lose weight", but try the higher number. It will likely work just fine, and be EASY--and isn't easy the same as sustainable?