Because I tried out xenForo and was pretty active on their forums before buying it. Its created by the 3 key people who used to work for vB, Kier, Mike, and Ashley... vB is suffering because they left. Like how vb 4.1 was released and then they released 2 patches within 24 hours which should have been fixed in the beta... tells you they are struggling. Also xenForo's unique features are great, sets it apart.
