The posts about the System/360 consoles come to mind, for example. I’m not sure how “popular” those were(?), but they’ve been very helpful as references for an art project I’m working on!
If we are going by the number of users, Facebook has more users than Twitter and Threads has about the same order of magnitude, but we still see a lot more Twitter submissions to HN compared to Facebook and Threads[1].
If users prefer the microblog format, Mastodon and Bluesky appear to be the most compelling alternatives, both have been steadily gaining users[2].
[1] Submissions from various sites:
https://news.ycombinator.com/from?site=twitter.com
https://news.ycombinator.com/from?site=threads.net
https://news.ycombinator.com/from?site=facebook.com
https://news.ycombinator.com/from?site=bsky.app
Not sure how we can find the number of Mastodon links since it has so many domains.
[2] Mastodon and Bluesky user counts:
https://mastodon.social/@mastodonusercount/11213120632905851...