Going lo-tech, and easy, I had the best luck with sand substrate. I've used gravel, eco-complete, sand, and organic soil with sand cap.
Gravel: PRO. it's really easy and fast to use. Just give it a good rinse and then put it in the tank. CON. My plants never thrived in it even using root tabs and liquid fertilizer.
Eco-Complete: PRO Again it's easy to use. You don't even need to rinse it, just put it in the tank.
CON, It's very expensive and for the price I paid my plants didn't do as well as I thought they should, once the fertilizer in it is gone you need to use root tabs.
Sand: PRO, My plants do great in it, my cory cats love it, it's relatively easy to keep clean, and depending on which brand you get it can be cheap.
CON, nearly every brand of sand needs to be cleaned, if you do not clean it, and do a through job cleaning it, you will have a sediment cloud in your tank, and that sediment cloud will coat everything even after it settles down. It's inert meaning you will need root tabs and liquid fertilizer right off the bat.
Organic Soil with cap, PRO, plants LOVE it, cory cats and other bottom dwellers also do good with it. It's meant to have a bit of a dirty look but is still easy to clean. It's not that expensive to set up and it should be self sustaining so root tabs shouldn't be needed.
CON, it's a bit of a pain to set up, the wood and perlite need to be gotten out of the soil, and the sand (if it's used for the cap) needs to be cleaned. Follow the instructions on how to properly set one up, or you might end up like I did when I first tried on, hating the tank and regretting I ever even heard about natural planted tanks. You'll need a great light, and a proper balance of plants, or you will likely end up growing algae till you want to pull out your hair.