IPB, Xenforo and VB all are great. They each have the own strengths and weaknesses it all depends on what you are wanting them to do. I have all 3 on different sites and find that there isn't a lot of difference in them as the missing apps or hooks are all available whether by the developers or 3rd party so they are all just about the same. It just depends on what you want them to do and how much you are willing to invest in time and frustration on making them do what you want them to do. I am not so sure about IPB 4.x though hopefully it won't be a cluster fxxk like VB5.x is/was. Anytime a developer completely rewrites a piece of software there is going to be bugs and glitches just have to hope IPB won't follow in VB's path of ignoring the bugs and hoping the end-users will come up with the fixes