Mastodon wasn't really ever the "only game in town" but it was the only game polished enough that a lot of people could probably figure it out.
But I think Calckey is now a side-by-side contender. Like at this point, I wouldn't recommend one over another anymore from a user experience standpoint. I think Calckey actually looks more approachable in some ways.
Though I haven't looked at server moderation capabilities of Calckey yet, and that's one of my remaining concerns.
