A blend of all 3 of those would benefit you the most, as each has it's own unique amino structure, whey is high in bcaa's, soy is high in glutamine, casein in the 8 eccential aminos, also egg is often forgotten but shouldn't be is in imo still the best form of protein.
One tablespoon of each of the 3 you mentioned will provide about 11-12 grams of protein each, I would mix them together with a healthy oil like extra virgin olive oil, or even half and half, or 1-2 tbs of heavy creme. Fat is needed for efficient utilization of protein.
These brands all are inexepensive and HQ, Optimum nutrition, Puritan's pride, anywhey, always look for the largest size available, as you always save more money when buying in bulk. DPS nutrition has excellent service and I personally have been ordering from for 5 years now. Soy protein is usually cheapest in price at your local health food store, all others are cheaper online.