I used phpBB for several years, from 2008-2012. It worked well, no complaints, though it is not update that often with new features. Then I upgraded to vBulletin 4.x. It also worked well. But by 2014 or so, development was completely frozen.
I purchased a XenForo license and started test migrations to XF 1.4/1.5 in the 2015 time frame. But I also decided to wait until XF 2.0 (a MAJOR upgrade/update) came out to migrate. Then, I decided to wait until XF 2.1 (another MAJOR update) came out, and I finally migrated in March 2019. And haven't looked back since.
There is so much information out there about the pros and cons of various forum software, that NO ONE should be requiring others to do their homework for them.
XF stands very squarely on its (many) merits --
- the forum industry's most knowledgeable and experienced developers
- the best technical architecture/foundation of any forum software out there
- very active and responsive tech support (as well as forum-based support here)
- very active third-party developer ecosystem for add-ons
- regular updates and new capabilities (typically every two to three months)
- great support for importing from other forum software
Just look at the market share growth (and migrations from other forum software) to XF over the past few years.
XF is not a bloated "everything and the kitchen sink" type of forum package. That's what vBulletin did with version 4, and it turned into a literal hairball of code. XF is developed thoughtfully, and methodically.
Certainly there are some other great forum platforms out there. Some cost money, others are free or near-free. If you need "convincing" as to the right forum software for you, the first and best thing you can do is to have a clear picture of your own goals for your forum, and for the needs and desires of your forum members. And once you have that, a forum software solution choice will become obvious. And maybe your decision is to stay with phpBB or whatever forum software you are already using -- that is a very valid solution for many people !!