The substrate pellets are good for heavy feeders like swords. I don't know the AquariumPlants brand, but from their reputation I would assume they are fine. I use the Seachem Flourish Tabs. BTW, it is much less expensive usually to buy the Flourish products online. I buy the largest sizes of the products I use, with all my tanks. A 2L jug of Flourish Comp is $70 in local stores, but online I pay $33 and this lasts me just over 12 months. Add to this the savings on Equilibrium, Trace and the tabs, and it is a couple hundred dollars saved.I wanted to initially get the Seachem Flourish Comprehensive but the only brand the LFS had was the Tetra and I wanted to get some kind of fertilizer in as I hadn't fertilized any of my plants yet. I'll look elsewhere for one of the other two. I did purchase from Aquariumplants.com their substrate fertilizer pellets and put one down between my ruffle leaf sword and the Bleheri Sword. Aquariumplants.com is where I got my plants from as well. But, I will try to find one of the other two fertilizers you suggested.
Will I be able to see any new growth from the crown of a Vallisneria? If I don't, should I let the melting leaves just hang out in the water until I do or should I take the leaves off as they get yucky? I don't want to yank them out if I know at some point there might be new growth.
On the Vall leaves, I would leave them unless they are definitely dead. If the base of the leaf is brown, nutrients cannot pass up and down so no point in leaving the leaf. Some nutrients are what we term mobile, meaning that the plant can move them from a dying leaf to new growth, so here there is value in leaving the decaying leaf. But once the leaf stem base is brown/rotted, this can't occur. If the leaves are truly "melting," turning into a pile of mush, they can be siphoned out and I would remove them by this stage.
Byron.