It is going to take a lot to compete with a company as large as vBulletin. vB is by far not the only one there, IPB is a very formidable competitor, on the free side there is PHPBB, SMF and countless others. vB has the largest because it is still the best (IMO) and has an enormous amount of third party support. There are a lot of designers, skinners and developers for it, you will never be a serious competitor until you have that, its as simple as that.