The big winners of this so far have been ActivityPub servers, especially Mastodon, and micro.blog, where I’ve seen a lot of people finally jump out of the boiling pot (I was gonna say “frogs” instead of “people”, but the whole right-wing frog avatar thing…). My handles are in that About page above you, if you want to follow.
If you’re picking an ActivityPub instance, be aware that mastodon.social is a giant possibly-hostile mess like Twitter, and not really a “community” like many other instances. Pick a smaller instance, read the timeline on their instance’s front page, and make a more informed choice. You can communicate with almost everyone in the Fediverse and see a similar Federated timeline from almost any instance, but the Local timeline will be different.
If you were on ADN, you can ask me for an email@example.com invite. Pleroma is also interesting, and might be more to your taste.
Anyway, welcome to the free world, ex-twitterers!