asking that question is like asking what is the best sexual position, who makes the best condom, pepsi, coke, mtn dew, dr pepper, ass or tits.....
The are toooo damn many variables to answer it, like what plants, temp, pressure, water quality, trace elements, set up, what is your res made of..... you want to buy locally or internet, how much is shipping are we looking for plant size or weigh potency ,....
basically what i am saying is buy something try it in your system, then get something diff and try it using the same clone plants and a year you will be able to answer that for yourself.
i wish i could throw out a brand that is far and away the best but there just isnt a simple answer.
e.g.
best for under 30/gal cns17
best to hide in the masses of reputable hobby hydro growers flora nova by general hydro
best that you can get at walmart/ hd schultz.
for my money i use cns17 and add what my plant tells me it needs.