The commercial broilers that you are (probably) looking at are ready to harvest at 8-12 weeks of age. At that age, the hormones have not had a chance to really start flowing yet, so there is no difference in the taste and texture of the meat between males and females. The males however do tend to grow larger/faster than the females, which is why the cost more. Many people who raise meat birds find the males more desirable because if they order only males they will have larger birds and all of their birds will be roughly the same size when they are processed. They're willing to pay the extra for the uniformity. If you buy straight run, then it's usually cheaper but at 8 weeks there could be several pounds difference between the males and females which means that you will end up with a freezer full of slightly differently sized chickens. Some people butcher the females a little earlier (4-6 weeks) to get the small "cornish hens" like what you would buy at the grocery store. It's not really that males or females are better meat birds, but more about personal preferences on finished size and uniformity of the batch. If it's your first try at meat birds, most people (even those with a definite preference for one gender over the other) would recommend getting straight run and seeing if you have a preference for one gender over the other.