Everyone has their own opinion on which substrate is best, so i don't think your going to be able to find a black and white answer.
I used flourite for a while, and it was great. Only complaint was that it was extremely challenging to clean before putting it into the aquarium.
I just purchased 150lbs of turface for my 150 gallon tank, and it only cost me $13 per 50lb bag. I decided to try turface because of the huge difference in price (compared to flourite or eco-complete), and from what i've heard, it's a pretty good option if you're on a budget. The only complaint that i've heard about it is that at first, it doesn't all stay at the bottom too well because the grains are so small, but it eventually sinks down.
I haven't used eco-complete yet, but i know a lot of people on this forum use it.