I prefer a base Miracle grow organic potting soil covered with a top presentation layer of what ever I like the looks of best. Sand will show any of the potting soil that gets dug up and gravel will hide any dug up soil.
I preferably like sand more than gravel for planted tanks. But the thing I would actually like the most to use is this type of gravel that petco uses which is their standard sold in store gravels very finely grinded. It is like a rather coarse gravel more so than a sand. Petco uses it in all their plant display tanks near me. This stuff just looks amazing! I really like it and it comes in colors of white and black and maybr more ive just never seen any more. Check your local petco if they sell it as its amazing! It costs $17.00 a bag for a 20 pound bag. So its in the more costy end of substrates. Good Luck!
Depends on the fish you keep as well. Any cats or rays do sand for sure. Think of the contrast and the look it will give to your fish as well. Me I'm a sand lover for planted tanks, I had the most success with a natural river sand