I'm going to vote vBulletin simply because I prefer the better features. However, most people think vBulletin is a beautiful piece of coding. As a programmer who has a LOT of experience with vBulletin and is concurrently learning business-oriented programming... I'm going to flat out say it...

vBulletin is an awesome program on the front-end, but the back end is very duct-taped together and uses very poor coding practice.

I'll admit the features rock, it's very skinnable (I love template conditionals!), the admin section is amazing, and it's easy to integrate with.

Regards,
Patrick