People have found success with lots of different substrates, which is why you have seen so many different set ups. Substrates fall into two general categories, active or inert. Active substrates include dirt and aquasoil and provide the plants with nutrition (though many people add supplemental fertilizer also), but they change over time - they may leech too many nutrients right at set up and they eventually become depleted. Inert substrates like gravel and sand have no nutrients, so you have to add the plant nutrients yourself. There are many pros and cons to each well beyond what I've explained here, and a lot of it comes down to personal preference. The most important thing is that you understand the properties of the one you go with, because they aren't managed the same way.
I will make a few comments though. If you choose to have a dirted tank, you must have a cap of some sort. This is not optional. ADA aquasoil is a popular choice (though it's not the only aquasoil in town), but you won't see many Americans using all their extra additives because they are super expensive and I don't think the advantage of using them has been proven. I'm not clear that power sand is functionally different from using crushed lava rock as a base, which primarily allows you to get more substrate volume without having to buy an entire dump truck of aquasoil ($$$). If money is literally no object and you want to try them all out, sure, go for it. I'm sure they are fine. But for most people I think your money is better budgeted elsewhere.
