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.
Iceshrimp (Misskey fork) did not rebase their version of Misskey. They’re still based on the same Misskey v12 era code from Firefish and there’s no interest in significantly updating the JS version (as it’d make migration harder) now that the rewrite is well underway and (in my potentially biased opinion) quite promising.
If you’re on a single-user instance, and can limit yourself to apps targeting the Mastodon API, it’s quite usable. The web frontend still needs a fair chunk of work, and moderation tooling required for larger instances are still not there yet. (But there’s enough to fend off spam)
The only features kicked out from the Misskey fork were, from what I remember, post imports (which were broken and leaked DMs (Sharkey’s on the other hand should work fine, as their implementation is unrelated to the Firefish one)), and the centered view in the web front-end. The rewrite may end up removing more features, it’s still not exactly clear as more important foundational work is needed before decisions like that can be made.
Sharkey’s Mastodon API was I believe more or less a direct port of the old Firefish one. (And, yeah, it’s not in a pretty state right now.) Firefish’s implementation has since gotten replaced with the implementation from Iceshrimp some time after Firefish was handed off to Naskya (which may just be the only Mastodon API implementation on Misskey-based software that actually works).
This is way too much of an oversimplification that I would plain remove this claim altogether. All I can say is that Sharkey/transfem.social has had a change of ownership and things are more or less resolved now.
CherryPick is older than Sharkey, and Korean (from what I know, anyway)
Thanks for yours and @JupiterRowland@sh.itjust.works’s deep dive into this!