I would choose to save the account with the most information in it with regards to past stays, credit card association, correct mailing address, etc, but it really doesn't matter. The highest elite level will be transferred to the kept account along with the points. Since HHonors says that combining accounts is irreversibale, I would get rid of the account with the fewest points. That way in case there are any problems, I am not on the phone trying to find cyberspace lost points talking to multiple agents and faxing in lost copies.

In practice however, I have done several of these combines for family members and they usually go pretty smoothly. HHonors only took a considerable period of time when people had created lots of new accounts with the 50,000 point bonus offers.