Looks like Kbin is running a pretty huge federation backlog, as it's taking several hours for comments to federate out. I'm not knowledgeable about how these servers work, but is it teetering on collapsing or something?
Really just the big ones. Lemmy, Mastodon, and Misskey. In my humble opinion, judging by the software alone, Misskey > Mastodon, kbin > Lemmy. Judging by the culture is a lot harder because it depends on the instance.