Eco-complete is a great substrate, I would only change if you are after a different look, as black doesn't suit all tanks. As Nry says tropica plant substrate gets good review, band as you top it with gravel or sand you can have any look you want. Most of the 'complete' substrates work well. Laterite is perhaps one to avoid, its ok but doesn't really supply anything other than iron, the 'complete' substrates provide a range of minerals. If you want the best the ADA aquasoil is top gun, but it does lower the pH so probably best for the more experienced fish keeper.
Sam