Its a neverending story- a cats/dogs, BMW/Mercedes.... kind of thing..
As a beginner i worked my way through all ( well, thats impossible but a lot) of info about soil/substrate. I decided on the info i gathered that there was nothing speaking absolutely for akadama, so i tried a few cheaper things first and ended up with a mixture of clinoptilolite, terramol, vermiculite and a bit of organic material ( a bit depending of the tree). I am happy with this mixture and my trees are happy. You can go on and on about it all , and some will say that only akadama is the real thing, and if you use cat litter ( terramol) you are not really doing bonsai, etc etc. Just keep and open mind, be objective, try some things and use what is best for you and your trees.