Was the best until 2009, but then the developers left and it's been rubbish since
We are still using vBulletin 3.8 having been a vBulletin customer since 2001. It used to be the market leading software with good reason, but in 2009 the original development team left (all but one) and the replacement coding and management team has been very poor. What was needed in 2009 was a complete rewrite. However vBulletin 4 was vBulletin 3 with code 'updates', and vBulletin 5 connect is vBulletin 4 with code 'updates'. It took years before vBulletin 4 was considered a reasonable forum solution, and vBulletin 5 is truly terrible. Way too many queries and css definitions. Full of bugs just like vB4 was on release. We're migrating away from vBulletin as soon as possible, having seen that vBulletin 5 is not a viable product. In summary. vBulletin used to be the best. Now it's terrible. AVOID.