Both Discourse and NodeBB would require a VPS (Discourse runs on Ruby on Rails; NodeBB runs on node.js). There are PHP clones, of course, which would allow you to run on garden-variety LAMP-stack shared hosting, but I can't vouch for any of them in terms of anything under the hood (there are lots of "appearance" clones of just about all popular web software, but beyond a vague surface similarity they're often not much like the original at all, especially where performance is concerned).
I'd suggest putting together a feature list first. Do you want flat or threaded? "Karma" system? Auto-promotion of "trusted" users to moderators (or mod-like users)? Navigation? Discoverability? Topic segregation? Auto-archiving (time-based closure of old threads)? Merging or redirecting duplicate threads? Anything else?
With a feature list in hand, you can look for something that checks the most (and mot important) boxes. Almost anything can be skinned to look good and improve the UX somewhat, but for deep features you're at the mercy of the underlying data structures - and fixing them up the way you want them can be more difficult and frustration than building the whole shebang from scratch.
Thank you for all this information. After looking around a little more, I realized that the default look isn't as important as the feature set (as you said) For the hosting, I don't really mind using a VPS.
For the features:
Flat
"Karma" system
I am indifferent to the auto-promotion of users to moderators (like discourse trust levels).
For the navigation, I would prefer to have a recent threads page as the home page with a separate category/topic page.
I suppose auto-archiving might be useful in the future.
Merging duplicate threads is a must have.
I would like to have social media/external sign in options (Gmail, Facebook, etc.)
I definitely will expand my horizons to look for these features. Thank you for your help.
