In my view this is one that depends on what you want it to look like in the end as plants grow in almost any type soil. Some is easier to make the plants stick until they get rooted fully but that is more of a user friendly type thing to me.
So the question may be more what looks right to you as we all have different experience with water and shorelines. Do you see the bottom as one single thing like a smooth sand beach like along the ocean or do you see it as a wide mix like found on the creek bottom? Do you see the bottom as something to look more "natural" for your experience or does it serve to highlight the fish colors?
I'm more creek/river guy so a mix is right for me. Hint? I also tend to go the easy way when available so mixing is fine with me as I don't have to make an "all-in" decision but can feel free to add this or that and not even worry if the planted pots get knocked over and spill some dirt in the sand, gravel Flourite mix!
Until you get into some of the really fussy things that really require special treatment, I don't find the sub on the bottom to be a very big factor when compared to all the other points I need to master. In the yard, the soil type is much more important as different kinds work different when it rains or gets too hard but in the tank there is no drought or rainy season to consider!