"You can do much worse than 75% one of these and 25% AAA spag or Coconut husk."
If you live in an area that gets frost, coconut husk is an extremely bad soil ingredient. It turns to a slimy mushy mess after it thaws from its first freeze. That slimy slush will hold alot of water, which will rot roots. Don't use it. Don't even think of using it, if you get freezes.
Turface is a very good material to use, especially when pumice and lava rock cost triple what it costs per pound--IF you can find a reliable appropriately sized supply.
The best mix is the one you can find and pay for and drains well. This largely depends on what's around you. The bottom line for a soil mix is that it has a components that drains well, but holds water, and is durable. I use expanded shale (haydite, and/or Turface, crushed granite and/or swimming pool filter sand and baby orchid bark.) I've also used brick mulch in a pinch (if you use the smallest particles), and an expanded shale product that was originally intended to deter gophers and moles from digging in gardens. Once you're familiar with what a good bonsai soil looks and feels like, you can riff on what can be used based on what you can find and what's affordable.
There is no "perfect" bonsai soil, by the way. All have their strengths and weaknesses, but some are weaker than others. Contact the local bonsai club and see what they're using.