Thermagize XT and Lean Edge are in all of you stack options and are a great foundation.
So it's really deciding between MitoBurn XT, Thermo Scorch, and TTA-500.
If only choosing one out of this group, I would go with Thermo Scorch bc it contains the most active ingredients.
I would pick it over MitoBurn XT because ThermoScorch has a month's supply of 1,000 mg. per day of MitoBurn already in it + Sinetrol, CaloriBurn GP, Capsimax, and more.
You could add MitoBurn XT to it and use extra MitoBurn on top of Thermo Scorch, but before doing that, I would add Reduce XT. The reason for that is that it's the same price as MitoBurn XT and it targets fat loss from a different angle, so since you're already getting 1,000 mg. MitoBurn in Thermo Scorch, I'd go with Reduce XT to target fat loss a different way.
TTA-500 stacks great with the above stack.
Actually, there's a promo until the sale ends too where if you buy a Reduce XT discounted multi-pack, you get a free bottle of MitoBurn XT with it.
I hope that helps.