[deleted] Also, I haven't had a very good experience with Discourse support. They don't have very friendly moderators on their help forum, and sometimes when you question them about something that they replied to, they threaten to ban you from their forum. This isn't something that Flarum does! ???
I used to antagonize the dev team a bit over design and performance issues when Toby was running the show, and nobody on the moderator team showed me their fangs; they dealt with the criticism in a mature way.. there is a very good team here, not just moderation wise but in terms of relaying technical information, setting expectations, etc.
I work as a linux server administrator and web developer and think that this team's professionalism is pretty impressive considering that they are still working for beans at this time.
I've tested both discourse and flarum. Discourse is significantly more advanced but it's achilles heel is that it was written in Ruby, which is an utter pig in terms of CPU and memory usage.. and is also rapidly losing popularity. Therefore, your discourse forum is basically a ticking time bomb if interest in ruby continues to tank. The dev team backed themselves into a corner with that choice.. and also, based on my interactions with them, they are huge snobs..
Flarum has a ways to go, but it's written in PHP, a language with massive adoption.. that had a dip in popularity but is a rising star again lately as the performance keeps improving lately. It is also written in the most popular framework. If you want your forum to last.. flarum is much better in regards to future support and plugin development.
I have been watching flarum for years.. i really think this team has what's needed to turn this into something great... they just need more funding and thus more man hours devoted to development. As for my choice on where to migrate my massive 14 year old forum, I'm still split between vanilla forums and flarum.. vanilla wins on features i need but i've seen that it is kind of buggy and the team isn't very professional or cohesive. That's a huge negative for vanilla.
I've seen all the forum software out there and i think flarum holds the most promise and has the best team. I think flarum is the best choice around today for most forums.