Depends if you want to go to a Grow Shop, or if you want to go to a garden centre.
For general growth a nutrient ratio of 3-1-2 (N-P-K) is ideal. Some people like to add boosters during flower, which are generally nutrient bottles that have zero Nitrogen in them, just Phosphorus and Potassium, most nutrient companies do a P-K13/14. This gets added to your normal nutrient in smaller amounts to change the ratios of the elements you give to the plant.
There are nutrients by Bio Nova, Biobizz, Canna, Advanced Nutrients...the list goes on. They are all much of a muchness imo when it boils down to it. You could just go to a garden centre and buy their own brand of houseplant nutrient as well. Just check what the available % of N-P-K are. I actually use organic fetrilzer for conniffer plants.