I really don't like PhPBB, it is too basic and doesn't have many features, hacks are hard to install, etc.
And I love Invision. But I am using a free service, and after all of that, I am doing good, and I enjoy it. And I am bad installing codes/hacks etc, so it's okay with me to use Invision Free.
About VBulletin, I think it is excellent. But it is expensive and I can't pay. If it not were for that, I would use it.