The below feedback has been solicited from the current Arch Linux Forum team in October 2019, based on the premise that the DevOps team desires to replace the current forum software.
The points have been summarized for readability, and anonymized to ensure the points are considered based on their merit alone.
Our preference is that a demo system is set up prior to a final decision being made so we can evaluate the moderation tools available to assess their suitability for our community behaviors.
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phpBB
*
https://www.phpbb.com/ * Seems still actively developed.
* Is listed on some "top 10" forum software for 2019 sites.
* It is very similar to fluxBB.
Thredded
*
https://thredded.org/ * It is actively developed
* Free & open-source
* Has a 'modern' visual style (while being readily customizable/themeable)
Can be used with a SSO
Paginates
Demos I've found load quickly and are easy to read on a TUI.
MyBB
*
https://mybb.com/ * Maintained
* Has an LDAP plugin.
Farum
*
https://flarum.org/features/ * Seems to be similar to discourse; claims to be lightweight.
* Has SSO, API, and Anti-spam.
* Still beta release.
Vanilla
*
https://open.vanillaforums.com/ * Maintained
* Open-core/Freemium model.
* Has SSO.
Misago
*
https://misago-project.org/ * "Looks OK from a bit of playing around on their site. Not sure what moderation tools look like."
Discourse
*
https://www.discourse.org/ * There seems to be a lot of bells and whistles that increase its complexity but I have no experience with it.
* Discourse ... design philosophy seems to be in the mindset of catering to the majority who have high powered systems, good network connections, and "modern" (GUI) browsers. The Arch community has always seemed to work hard to not needlessly marginalize those who have limited bandwidth, old hardware, or text-mode browsers; so the use of a tool like discourse strikes me as either antithetical to our existing community ethos, or a sign of a significant change in direction.