Asking what the best planted substrate is just like arguing semantics.... Everyone who has ever had a planted tank will have different opinions on which substrate they think is best, and the "plain jane kitty litter" guy it's quite obvious you never did your research on kitty litter brands and which are fired, and which are actually natural laterite based forms. Special Kitty: All Natural kitty litter is 100% aquarium safe, is made of natural laterite, and doesn't break down after use. I've used it for years in my planted tanks without any issues of having to add more because of breakdown, and it has a high CEC ratio which is what you want from a planted tank substrate.
PFS (pool filter sand) IMO is nothing more then a top layer substrate to planted tank enthusiast, 90% of people with planted tanks will tell you they use sand to cap their first layer of substrate. Such as using say SeaChem Flourite planted substrate as the bottom layer of your substrate, then adding sand for the top layer so you don't see any flourite.