When comparing PHPBack vs XenForo, the Slant community recommends XenForo for most people. In the question“What are the best web forum software packages?” XenForo is ranked 7th while PHPBack is ranked 12th. The most important reason people chose XenForo is:
Good stability and functionality.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Multi-language support
It has been already translated to Spanish and they are adding support for more languages.
Pro Easy setup
PHPBack is very easy to setup, all you need is a server with PHP5 and MySQL installed.
Pro Open Source
PHPBack is open source, uses GPLv3 license.
Pro Stable
Good stability and functionality.
Pro Fast
Works really fast.
Pro Lots of styles and extensions avaible
Pro Extensible
XenForo is built to be the most extensible and flexible community software ever.
Pro Stable, well written, developed by the guys who once made VBulletin 3.x the best commercial forum software at the time
Price is only $140, one of the "cons" claims it runs up to $610 if you by all t he bells & whistles, but scarcely anyone pays more than $140
Cons
Con Small community
PHPBack is fairly young (first stable version was releases in July 2015). Currently the community is small, which may make it more difficult to find help/support.
However, the developer is active on the github page and generally responds quickly.
Con Expensive
140$ for simple use, price can reach 610$ for complete system and service.
Con Closed source
Con Unique SQL system
Only MySQL system.