ADA Aquasoil is my favorite, it's the only substrate that really is loaded with nutrients. It's not much more expensive than Eco-Complete and the results are better, no need for the substrate to age and no need to dose for the first month couple of months.
For larger tanks Turface/SMS would be my choice. Requires nutrients to be added but if you treat it the old fashioned way (light dusting of peat and/or laterite) and dose on a regular basis you'll likely get better results than with Eco or Flourite. Much cheaper than the other plant substrates.
I've been playing around with zeolite sand and the results so far are good. Again no nutrients present but it acts as a crazy nutrient sponge.