Both BB software are user friendly. Only the major difference is price phpbb is open source and you have to pay for vBulletin.
Both software are search engine friendly and has an active strong community for support and help. I would say it’s all your decision what you like or not coz both software strongly capable to do there jobs.
Here is the feature list for phpBB http://www.phpbb.com/about/features/
Here is the feature list for vBulletin http://www.vbulletin.com/features.php