IRC is nice. The really simple technical requirement to access IRC is still a barrier. (30 years+ later!)

Not Reddit. Reddit is gone, it used to be nice. Maybe some extreme niches are okay, but generally, no.

HN is okay for now, but is getting popular. We're already afraid of bots and state actors when we get posted on Chinese social media....

4Chan is 4chan, some niche boards are great, but media bias.

*chan derivatives, lean far to one side on the political spectrum. Great to compare and contrast, but who knows what the intention is.