I've used both. vBulletin is the standard by which all other forum scripts are measured. It can be difficult to learn it's many features, though. phpBB is very easy to setup and maintain, but it lacks the sophisticated features of vBulletin.
I agree about the complexity of vB - a good thing and a bad. Sounds like it'll come down to how much work you want to put into it. I recently upgraded a site to vB3 and the subscriptions option had turned the site into a money maker.
__________________ Please do not PM me for support or sales questions. Thank you for your understanding.