Fabian, What events do you do? What is your current height/weight and ~bf? I wouldnt trust any thermogenic products. They will almost certainly contain banned substances.
I agree with Matt though stick with those basics, with two additions.
1. Citruline malate if you are a long sprinter and up.
2. Cordygen5 if your aerobic capacity is lacking. Makes aerobic work a breeze.
But be sure you check the ingredients. You can check here as a start. https://drugfreesport.com/rec/index.asp?accessdenied=/rec/rec-tools/supplement-inquiry.asp
You can submit a supplement and they will respond via email with info on whether it contains any banned substances. Passwords NCAA1, NCAA2, NCAA3.