Hello Tim, welcome to Bella!
Cannot wait to see what you are creating!
As a general rule use the layer in the material when trying to get the more realistic result, because layer interacts physically with the base, depending on light angles and material parameters.
Once you use the mix materials (blend / stack) will be applying the weights you’ve chosen, even textured, but each material do not interact each other. Therefore, that’s more artist-based.
So it’s up to you what to pick in each particular case.