both are leaps and bounds better than phpbb though, which is what this site currently runs on.
the core feature set of phpbb is pretty limited. you need an extension for almost anything. also, the extension community is hostile. it's a waste of time to even contribute anything. they make you jump through too many hoops and lock your stuff in "abandonment hell" if you're not on there all the time. i have also had pretty negative experiences with devs who won't accept very common-sense pull requests to improve their stuff. they're petty.
the discourse dev/support community is awesome in comparison.
if i had to guess, what's really holding phpbb back is resources though. they don't have enough dev time (either paid or volunteer) to improve it to the point of being competitive in the current landscape. i think they'd probably need to do a total rewrite.