I prefer a forged high carbon hawk whether the whole head is high carbon or only the bit. There are several HC steels that can be used. 10XX series steels are great as well as some tool steels that are forgeable. The heat treat and geometry is key to a good hawk.
Actually the steel is a relatively small part of the over all worth of a hawk or any tool. For example, if the above qualifications were spot on and yet the handle was not shaped correctly or, heaven forbid, loose on the haft, the other good qualities are null and void.