[BJBBB]

HN is one of my most beloved sites. It also infuriates me; and this is not a bad thing. I do not mind the down-vote if the reason is apolitical and explained. [aside note: Gackle and Bell are interesting - they are worth 15 or 20 min looking at DDG links.] And 'Dang' responses seem to be sincere at their attempts to keep HN a viable and reasonable site for techies. While I think that a few of their responses border on hilariously ridiculous, they seem to be earnest.

My answer to your question is, other than HN, probably nothing else is reasonable.

While HN is mostly by and for coding peoples, it oft provides interesting discussions of engineering, science, and society. My remaining favorite discussion forums are densely technical and increasingly narrow in scope, so would not meet your requirements.