All of the cornish taste the same. The only benifit of roos is that they grow faster... but they also eat more than the hens. The hens will only take about a week or so to reach age of roos. I would just buy straight run, butcher all the roos one week, and the females the following week. For 6 lb birds dressed, I butcher roos at 8 weeks, and females at 9 weeks.
As for flavorful, go with heavy breed birds of non cornish x variety and raise them till 4 months. Much sweeter, a bit tougher, and much longer till you can eat them though.