Well, I own a vbulletin now and I am far from happy. I have summarized my "joys" into a
blog post and there is also more: I had to move the forums to another server 2 days ago. Of course ALL my other scripts worked flawlessly, but not VB. I had the language messed up and the avatars are also gone.
I will buy an IPB license for a forum of mine that's on IPB 1.2 (when it was free). As outdated and non-secure as it is it's way better than VB in my books.
I also worked with myBB (cute script, too few hacks and developers still) and SMF. Which I hate with a passion.
I would like to remind you all that I am skin designer in most of the forums scripts and I tend to work on the forums a lot and modify everything. This is why I am not pleased with a set of features and that's why scripts that have almost all needed features don't make me love them that much. I like customization, not defaults :D