I know there are folks who are fans of Vanilla Forums, which might be worth exploring. A lot of next generation forums are using Discourse, which does not run in Reclaim’s cPanel, but can be setup in Reclaim Cloud. The downside of that forum is it can be a bit more expensive billed monthly, but the upside is it is pretty robust software.
As for other forums, I am not all that sure given phpBB and Discourse are the two I am most familiar with.
Yeah, not being updated for two years is a huge red flag, so steer clear and thanks for the heads up, I will stop recommending. In that case I think phpBB might be the most tried and true forum, and if it ever blows up and you need something else I imagine there is a migration route to other tools.
I can’t speak of too much experience with Vanilla, and very long ago experience with phpBB – I do see it in use a lot. I’ve done much with Discourse (what this site is running) and it does a lot but the management, setup, customization is a long learning curve.
Avoiding spam might be more a story of what the platform offers for onboarding and moderating new account requests. Most any site where any visitor can create an account to post publicly is susceptible,
Other solutions are using WordPress plugins that turn a site into a forum, or adding it in. I looked at this 2 years ago exploring the ones covered here 10 Best WordPress Forum Plugins (Compared) I found bbPress not usable (but forget why), BuddyPress is probably overkill- the free version of wpForo worked with the project (but then the client decided not to go with it).