When we first discussed setting up Fine Tuned Mac, we talked about several different options for bulletin board software.
I'm familiar with phpBB, vBulletin, Simple Machines, YABB, and a few others. Each has advantages and drawbacks.
In the past, phpBB and vBulletin have both been notorious for having security holes. I think vBulletin has gotten better in that regard; certainly they now advertise security as one of the product features. YABB is easy to set up, open-source, and free, but it's also ugly as hell and not very flexible from the administration end. Simple Machines is secure and free, though I don't have a lot of experience with it.
Ultimately, though, the choice for UBB was made largely because the moderators were already familiar with it and knew it inside out. Since the moderators here aren't getting paid for their efforts, and are helping with FTM purely on a volunteer basis (whereas I believe some of them at least were getting paid over on tThat Other Site before it was bought by CNET and shut down), I think it's reasonable to go with whatever makes their lives easier. I for one really appreciate their efforts here, and if using a familiar package that they don't have to learn from scratch makes their lives better, I'm all for it.