I have waited to see where the discussion goes & hear all the opinions.

I, personally, tried some of these apps: phpBB, Vanilla & some ASP-based ones that are not in the list.

phpBB is no doubt very mature & Vanilla is something a little different, like a new-generation forum.

I think choosing which software is very-related to the project it will be embedded to.

First I started with phpBB. Many features, nice to use, but many vulnerabilities at that time. My website got hacked.

I moved to Invision Power Board. Even more features than phpBB. But IPB became proprietary, and I wanted piwigo.org to run only with opensource softwares (Piwigo is GPL).

I moved to punBB. I think it was in 2004. A tiny set of features, but works like a charm. I’ve added some features for my needs. There was no plugin system so I changed the code directly (that’s bad, but I had no other choice at that time).

Then I moved to FluxBB, only because I had the feeling that punBB core team was also moving to fluxBB. Unfortunately, fluxBB seems to slow down (not dead, but I don’t see that much activity) while punBB has released new versions and so on.

If I had to choose a forum software today, I would give a try to Vanilla and bbPress. On wordpress.org forums, I’ve seen bbPress in action, and I think it’s really designed with user experience in mind. For Vanilla, I really like their introduction website (even if they should use PEM https://gna.org/projects/pem/ to manage their plugins) and how they designed the software with extensibility in mind.

I would definitely say that “simplemachines” forum is NOT to be on the list of recommended forum software.

1) Their security record has been VERY poor lately with thousands of poor website owners hacked and their sites compromised.
On the SMF forums, they constantly try to downplay this – both in always asserting that their software has no flaws, or minimizing the scope/or response required to deal with the inevitable hacks. That is why you will read of members being hacked over and over and over again, and their private information being released.

The other forums listed also have their security update releases too, but there (as open source programs) the discussion is frank and full-disclosure.

This allows you as a forum owner to take intelligently informed steps as to what to do for you site. With SMF, they will ‘sit on’ security information (even as people are being hacked left and right) before finally releasing ‘work around’ information.
The other thing I’ve found with them is: Because a ‘security scorecard’ is important, they tend to downplay security issues, even to the point of ignoring security reports from the security community. On several occasions, this has resulted in ‘zero-day’ release of information.

2) They are NOT open source – even though you can view and edit the source code, you can just give anybody a copy of the updated version: everybody has to go through THEM- for legal distribution. You cant release ANY code at all, so technically, even discussing the code (with relevant snippets) could constitute illegal (to them) disclosure. Every other week, they have long arguments where they ‘out sites’ for not displaying their link back… ridiculous!