Some substrates are better than others, ones like Fluorite and Eco-complete have nutrients and minerals in them that are good for the plants. Sand is good for rooted plants because it is easier for them to send roots out in than gravel is, BUT it is harder to siphon.
If you use good judgement on fertilizer and water changes a special substrate isn't necessary but it can always help.
I prefer to use Eco-complete in my planted tanks because its gravel-like (which makes it easier to vacuum) and it has the added minerals.
You can also have soil based tanks with gravel or sand caps. A lot of the big planted aquarium people I know like to do Fluorite sand or a sand base and a regular Fluorite cap. I find the fluorite harder to vacuum than E/C
I want to keep things as simple as possible. lol. I prefer the look of sand tanks but at the same time siphoning... I've seen a few youtube videos of people that siphon and the siphon on my tank isn't strong enough to lift gravel just fish waste so I'm not too sure how to go about things.