Hi there,
Feeding cannabis plants is a very extensive topic, beyond the scope of a grow question and deserves much research.
Personally, I have quickly learned that overfeeding is the most common mistake so take it easy with whatever you chose. I've now used general hydroponics and canna aswell as a few odds and ends. Both are great brands, but most reputable brands do justice.
The organic option can produce amazing bud, alot of growers I know go this route.
All in all, I would look into the specific requirements of the cannabis plant in terms of feeding. The 13 or so elements they require for proper growth can be difficult to supply to the plant. Growing in soil can simplify things a bit as, if amended properly, it can buffer most unwanted side reactions.
Lastly, think of feeding as one big chemical reaction, proper ph, growing environment, and lighting can be more important than "perfectly" feeding the plants.
I hope this helps.