Having used both, I personally think invision will be better the vBulletin one day. I don't know why, I just can feel it.

I did at one point, i used to be a regular at the ipb community but then i left when they turned into greedy *******s and broke all their promises. There was a time when it was a really friendly community full of fun...i go there now and its almost dead.

I think they have made too many mistakes in a short period of time and their whole reputation has gone down hill...it will be hard to pull this one around, vb has a clear market share/lead, ipb are going to need to do something big!