Being a coder myself, PHPBB offends every quality-control sense that I have.
The code is an absolute abomination, consisting of hacks on top of hacks on top of shoddy code. This is also why PHPBB has had numerous security vulnerabilities over the years, many of which allow complete access to your server. (Google for something like ‘phpbb hacked by’ and you’ll find plenty of forums that have been hacked)
A vBulletin license is $160 which is peanuts compared to how much can be made from a decent forum. Or even compared to how much can be made from a small forum.
I do use phpbb for a couple of hobby sites, but there’s no way I’d cut corners for a proper forum on a site designed to make me good money.