Honestly, it is hard to beat Norcodrene. It has a potent mix of appetite suppression and warmth (thermogenesis), with a very mild stimulant effect, that is hard to find in any other product currently on the market. This or E/C I think are going to be the most effective stand alone products.
Of course, others have listed many others that could be added to one of these to improve effectiveness.
No combination will work miracles though.