Hello!
Well, I've tried a few in my time; Atkins first, then Charles Clark, then The Carbohydrate Addicts Diet, Atkins (again), Charles Clark (again).
Each time, I lost weight and regained it when I stopped sticking to the rules.
This leads me to the conclusion that the simpler the rules are, the better chance of success.
In turn, this is bringing me to Paleo as the obvious choice for long termers.
I'm doing Anti X extra healing routine at the moment, as I have 3 key indicators for Syndrome X which need to be brought under control quickly.
I'm definitely leaning towards Paleo for life though.