Honestly, substrate isn't super important. The time invested in maintaining the tank is far far far more important than the perfect substrate.
My normal example:
My 55g tank with plain black diamond blasting sand and root tabs. I had more than enough time to devote to maintaining this tank and it flourished because of it.
I transferred everything to a dirted 40b and just don't have the time to invest in keeping my tank up to par anymore. This is how it is now.... That piece of mopani isn't helping things any with the tannins.
Now to actually answer your question. If I were to invest in a special planted substrate, I would choose Eco complete over pretty much any of the others.