I'm mostly responsible for a vb forum eve online corp, but it's a mess.
Vbulletin v4.
Person A held the hosting/ftp, now no longer with us, but occasionally contactable.
Person B bought Vb and signed up to it with his personal email, mega fail and now mostly AFK.
Me left to administer the forums as the only person vaguely techie that's still active.
Person B reappeared, ninja'd in some updates, and broke every skin and addon in the process. I've lost smilies! Now they've gone again.
Can't get support without vb account, cant download updates to skins/addons without it, cant apply them without the access to either ftp and the vb account.
Used to use phpbb. It had less community stuff and features, but I found it was a cleaner easier system to manage. I've found vbulletin a bit bloated, and some things like moderation priviledges are difficult to manage. But it has greater potential.