I have used Supernova and Exotherm and they both are good products to be honest. They work through different mechanisms though - how much do you have to lose/what is your current BF%? Have you used any prohormones or gear recently?
My feeling is that Supernova is a better long-term product, while Exotherm is kind of a more specific tool in the tool box. This isn't saying that SN isn't targeted and "complex" - just that the longer you use it the more browning you will get. If you have a lot to lose, then your fat cells probably do not function correctly and Supernova, over time, may help to get that back in order. On the flip side, if you're lean and need a kick in the pants, Exotherm may have more upfront impact because it has the mild AI function.
Both will provide results, which will be noticeable - but neither is going to be the complete answer. It's not like you will take either one and go from not losing weight to losing weight without having other things in check.