By which I mean in terms of usage, development, or stability. Also along those lines, which English-speaking instances would you recommend?
Interested as Misskey & forks have some feature edges over Mastodon in my opinion, but it’s somewhat harder to find discussion/info about them.
For instances of mainstream Misskey:
https://misskey.de (instance by maintainers of Friendica instances libranet.de and venera.social)
I’m using misskey.social from Italy, but they have some annoying limits for new or less-followed accounts e.g. how many people can you reply to in one post (this would shut you out from some discussions…)
For Sharkey:
https://blahaj.zone by maintainers of namesake Lemmy instance
https://calckey.world or https://sharkey.world by, well, .world
https://procial.tchncs.de
For Iceshrimp: https://fedia.social (from maintainers of fedia.io and infosec.*)