That's a 2 part answer based on your school of thought and I'll give you both.
#1: Your best flowering nute for a soil medium will be any broad spectrum base nute for the flowering cycle. My meaning here is a balanced, flowering specific N-P-K ratio. The Maxibloom series mentioned below is a good choice for sure @ 5-15-14. There's also Botanicare's various lines - the pure blend pro bloom has a 2-3-5 ratio that is somewhat similar. Essentially - any "all purpose" nutrient blend that is lighter on nitrogen and higher on phosphorous and potassium.
#2: Forget nutrient brands altogether because if you pay attention to the NPK ratios in each, then brand no longer matters. For the flowering phase of a cannabis grow cycle I would make differing recommendations based on NPK ratios for early, mid and late flower. Start first by transitioning from a base flower nute with a higher nitro mix (think like a 5-15-14 or a 2-3-5) in the early weeks post-stretch to a lower nitro mix (think like a 1-4-6) for mid flower. While the plant will need less and less nitrogen as it gets closer to chop, it still needs some so don't deprive it completely - similar to calmag supplementation. For the late stages I personally don't entirely cut out out the nitro but I have seen some who not only get rid of it altogether but also heavily cut back on the phosphorous and go with something like terpinator (0-0-4) for the final stages.
The simple answer for just about any medium is to find a balanced, flowering specific nutrient. As long as the NPK range leans more towards the P&K, you could buy basic tomato nutrients at any home or gardening store and it'll perform just as well as the higher priced, cannabis specific stuff. Good luck and hope it helps👍