Continuing the discussion from Why do you like Discourse?:
Hi @Agnete, allow me to reply to your message publicly because I think it’s worth praising Discourse. 
I have been using online forums since they exist, and tried a lot of different ones. Back in the day, my favorite was Caucus (http://caucuscare.com/, now abandoned apparently) which still provides unmatched features (e.g., the Caucus Markup Language that enables transforming the whole UI directly from within a specific “conference” and more generally to script the site for automation). As 100% of existing forums were way below Caucus capabilities, I never stuck to any one in particular, and was more driven to mailing lists.
That is, until Discourse appeared. One critical feature for me is that it’s free software using the Copyleft GPL license, guaranteeing that the code will remain free. It’s also programmed in Ruby, a language that I use, so it makes it easier for me to understand the code and modify it if needed. Discourse code is generally very high quality, which helps learning about best practices.
Besides the amazing community that you already mentioned, I think one of the best features of Discourse that makes it unmatched among its peers is the powerful quoting mechanism. With it you can easily start a response to any post, quoting as you write from any part of the forum: as the composer remains opened as you traverse the forum and topics, you can easily pick existing contents from all over the place. (You can also see how the ability to reply as a linked topic makes it easy to keep things organized.)
Another powerful feature is the ability to split and merge posts across topics and categories, so you can keep threads on-topic, refocus a drifting conversation into its own topic, and keep the place organized.
These features enable actual knowledge building, away from the growing mess of usual Web forums where the more the conversation goes, the more solutions get harder to find, leading to search engine pollution. With Discourse, you get the best of both worlds: a naturally flowing conversation and the ability to consolidate knowledge over time.
Other features facilitate this knowledge building, like turning a post into a wiki or, with e.g., the collude plugin, turn a post into a live collaborative editor like a pad – you can also embed pads via plugins (the plugin is pad agnostic, so for example at Librehosters we could adapt it to embed CodiMD with a single line change).
I’ve been using Discourse to collaboratively write complex documents over months of discussion. Ah, last but not least, Discourse uses Markdown (CommonMark) natively, which matches my usage elsewhere: in Gitlab, or to maintain static Web sites.
The Discourse team has all my respect and I’m grateful for their awesome contribution to the world’s digital commons.