Mine are mostly silk but for my 20G, I am slowly switching over to live plants. I'm trying to stick with the ones that don't require those uber expensive light setups. I have a T8 fixture and that cost enough! I also don't want to do the co2 thing either. I also use the tetra water wonder plastic plants but I take the bottom thing off and just let them float at the top of the tank. They provide nice cover and I find some of the bettas will just rest in them
Maybe your plants died because they required more light then you had?