My order of preference is Aqua soils (ADA amazonia/Fluval stratum) -> Caribsea Eco-complete - > Flourite
We often find our inspiration from nature, so we attempt to imitate it.
Aqua soils are literally made of dirt/soil turned into little balls, rich in nitrogen and great at growing plants, just like what we find in nature. Aqua soils also lower ph, gh, kh of the water making it slightly acidic, which most aquarium plants prefer.
All 3 are capable of good plant growth, but if I had to choose one, considering no budget, I would choose an Aqua soil, if I had a tight budget, I would choose Caribsea eco-complete.