Sort of depends on methods used to scape and plant.
Each takes some getting use to get the most out of it.
I like the ADA AS.
EC nice because no washing, but is lighter weight than flourite Black.
I have a large amount of Black flourite and sand. This is very nice and has a good color like EC. You have more consistent grain size and it's heavier(maybe 2x). It has two sizes: gravel(like plain flourite) and sand which is a bit larger than Onyx sand, which is just right.
You have to rinse it, there's some tricks that make life easier there though.
EC you pay more and you pay to ship water, always a bad idea, we can rinse, it's not that huge of deal.
Aesthetics, you could have argued in the past for EC, but not now.
I had noticed Eco was a bit more than the other two so I had narrowed it down to AS and black Flourite. My concern with AS was the ammonia produced on set up and whether my schedule would allow for daily water changes.
You can do several large water changes per week in the start......or not.........you can use Zeolite in the filter, that last about a month, you can add some media from an established filter etc, old established vacuumed dirt/mulm to a new tank, lots and lots of plants. And water changes............
All of these resolve NH4.
Doing all 3 and maybe 2x a week water change of 50% to start is a good method.
I haven't used EC, but I love my aquasoil. I did have a lot of ammonia and organics leaching into the water, but like Tom said, use those methods to reduce the ammonia, and you will be ok. Just dont add a bunch of livestock right away. I'm glad I went through the initial hassle with aquasoil, because now everything looks great. But like I said, I don't really have anything else except plain gravel to compare it to.
I ordered my aquasoil from ADGShop and it really wasn't too expensive. Plus, I think a good substrate is one of the more important places to invest your money in. My opinion.
Speaking of plain gravel substrate...that is what I have...is that OK for a low tech planted tank?
I have a 14 gallon tank with a 15 watt full spectrum light.
At present, I have one very beautiful male Betta and lots of green algae.
In the past I've had trouble with brown slimy algae, so the green is a welcome change.
However, I would much rather have a beautiful planted tank with no algae!
I also have very alkaline well water. I've tried changing it with pH correctors to no avail.
I'd really appreciate some advice about plant species that are easily grown and that would work well in my tank.
Do I need to replace my gravel, and if not, do I need to take it out and thoroughly wash it, or can I just vacuum it? It has lots of green algae covering it.