I really like the way youtube comments (and replies to comments) are organised. You can make a comment to the main post (a video), or you can reply to someone's comment to that video. Then the comments are ranked by likes, showing most liked comment (including its hidden replies), first. The replies inside someone's comment are flat, so its not threaded deeper. It makes it extremely entertaining to read the funniest comments first, and follow the flat thread in a comment is easy (just click "Read 14 replies").
Why don't forums, and Flarum in particular, not use this type of model? Flarum uses a flat quoted reply system, which, when there are many replies, get very long and confusing with jumps forward and back. In the case of Youtube comments and replies to the comments, the list is abbreviated a lot, because replies are hidden by default ("show 14 replies") and only the initial comments are shown.
Inside the hidden replies you can have a back and forth conversation about the comment someone made, but this personal conversation is hidden by default, but described by the comment title.
So youtube seems to have the best of both worlds, relevant and interesting comments listed first, but still provide the ability to have a back and forth discussion without that leading to a huge fragmented main discussion list, as in Flarum (and most other forums)
