Think of the types of plants you want to grow. Some plants wil grow great in Eco or Seachem others will only grow in Ada, Fluval etc??
Think of it 2 ways.
1) Organic ADA, Fluva, UP Aqua etc seem to grow the harder to grow plants well, Toninina Fluivitalis, Syng Belem, Erios etc
2) Inorganic substrates Secahem, Eco - Seem to grow Crypts, Amazon swords, Vals etc Well
Also the Inorganic are easier to vaccuum clean as they are heavier, generally get better with age as the have high CEC and act as magnets and hold in ferts nutrients, but also may become compacted like cement making it hard for plants to Grow.
Organic based substrates are lighter harder to root plants may become mush/mud later with breakdown, dont become compacted
Substrate is very important to most plants, although some plants do not need substrate ie Java Ferns Anubias Buce can be attached to wood or rocks and take ferts from the water column better and if planted too deep in any substrate will die. I have learned this the hard way trying to grow certain expensive plants that just dont like a specific substrate and they end up dieing and once I changed the substrate with all other equipment the exact same the plants grew amazing.
There are many DIY substrate methods that can be cost efficient and very effective ie
1) Miracle Grow Organic Potting Soil Methods Capped with sand and
2) Mineralized Top Soil Recipes on the internet
are thye 2 most popular ones right now.
Both methods may require more work and research for you but are cheaper and people have had very good success with these methods.
Choose the plants you want to grow first then work your equipment around that. I think that would be easier than choosing a substrate and then deciding you want to grow a specific plant that won't do well in that type of substrate.