If you don't have a strong preference, I would talk to my buyers. If the calves just go down to the auction barn, there are usually just a few order buyer guys that sit on the front row together and buy half the cattle week after week. I have never found those guys to be particularly unfriendly if you have some direct business related questions. Some barns REALLY favor the Black calves and some don't. If you THINK you are getting a price dock at your market, I don't have enough information to say that is not the case. I tend too want to say go with the Hereford and then come back with the Angus in 3-5 years; but I have not seen your cows, do not know your ranch conditions, and I know nothing about your goals or your market conditions so I am reluctant to make any suggestion.