Mastodon

The content is not strictly chronological, because you see content that people you follow repost at the time they reposted it, rather than in order based on the posting of the original content. It's more of an organic algorithm.

While I agree that this organic chronological ordering is better than the algorithms other platforms use, it's possible to overstate its impact. Remember that for a long time, Twitter was also chronological in the same way as its only option, and continued to offer that option today, though it tries to steer users to the algorithm feed (which maximizes garbage content as far as I can tell).

I would not say that Mastodon is designed to cater to smaller tight-knit communities, I would say that smaller tights-knit communities are more concentrated on Mastodon because those communities were to some degree avoiding the big platforms. As Twitter slowly dies, however, Mastodon's network will resemble Twitter's more, thought hopefully still be able to maintain the tighter-knit communities as well.

That's where I think federation adds a real bonus, giving individuals and small groups more power to control their destiny and shape— and even cordon off— their corner of the fediverse to their needs.