I'd say tildes.net, most project-specific forums (Discourse instances for FLOSS projects come to mind: Fedora, Let's Encrypt, F-Droid, Signal, and others), several mailing lists, and perhaps even lobste.rs are far more constructive.
I've noticed that HN is just like Reddit, Lemmy, and other up/down-vote based forums for threaded discussions in that it incentivizes one extremely predictable pattern:
Commenters have a first impression of what an article will say before they finish reading it, or before they read it at all. They take this anticipation of what the article will say, form an opinion about it, and search for comments that validate that opinion. These comments get upvoted.
Because of this, commenters have an incentive to not just validate common opinions about an article, but opinions about what an article may be about so they don't have to risk considering its content/views.
This phenomenon applies to the comments too, to a lesser degree. There's a recursive effect going on that promotes bikeshedding.
While it shares this characteristic, at leas the discussion quality is better than mainstream social media (FB, Reddit, etc); however, that's not even worth mentioning IMO because comparing a forum's quality to them would be an insult to said forum.
Several far less active forums like littr, subreply, gurlic, and tilde.news are far less toxic so some of this is probably most apparent with some popularity.
I will say that the moderation seems excellent, though.