I've used both, and without a doubt, in no matter what size tank I've tried both in, aquasoil is superior. But that's just my personal opinion. The AS does leach ammonia and lots of nutrients, especially in the beginning, but you can avoid any algae issues with lots of WCs. Also, the AS buffers the pH considerably lower for me, down to 5.5 from 6.8. That's a nice bonus for plant nutrient uptake. As for ferts, seachem is good but expensive, and I would also suggest dry ferts. Dry ferts are just as good, last for years and are less messy (just need a good set of measuring spoons).
Give me an example of some dry ferts and their' liquid alternative.. What I'm wanting ultimately for my' recently aquired eheim aquastyle 9 which also happens to be my' first planted tank... is a complete, inexpensive, high quality system of all the things I would need to keep this tank and make it look/maintain well..