I've used both at times and they work well not sure what tech level these people have. Seemed to me the my bb was more difficult to run from an admin side, but easier on the users. The phpbb set it was on we got a few more user questions, but it was a breeze to run.
If the person running it is way more savy than the average user go my, if everyone is fairly savy save the admin some minor headaches and go php.