No, it's none of them. I don't know about LegalEagle but Popehat and that Brummie guy who does constitutional law are already on Mastodon. Anyway, it doesn't matter who it is. That's not the point.
In case anyone is interested in a #TwitterMigration Best Practice, this is what I have so far.
1) Pick a Mastodon server that you think suits you, either based on interests or on geography, but whatever you do, for the good of the world and yourself, do not choose Mastodon.social as it's already far too full and so permanently slowed down. You won't like it.
2) Create an account with a name that is identical or similar to what you had on Twitter. At least for the first two months or so also use the same profile image and background image. It helps people from 'the birdsite' easily recognise you on Mastodon.
3) Run a tool to help you find your Twitter follows on Mastodon. It exports it to a CSV that you import into Mastodon. You'll be surprised how many people you followed on Twitter are already on Masto.
If you followed many people on Twitter it may make sense to run this tool once a week as more people may have moved since you last used it.
4) Put your full Mastodon handle in your Twitter Bio. It helps your followers, other people that stumble upon your profile, and most importantly tools such as the one in 3) to find their Twitter follows on Mastodon. If you plan to give up Twitter for good, have a link to your Masto profile as a pinned post for a while before fully closing your account so people can follow you to Mastodon.
5) Mastodon doesn't have verification schemes or Blue Tick stuff like Twitter. But, you can verify yourself if you have a domain name. By having a rel="me" link to your Masto profile on your website you will get a green bar for the link to your website. That way people know that the person behind the website is the same person as behind the Masto account.
6) If it turns out that you have chosen the wrong Mastodon server for you, you can always move your profile. Your follows and followers can move with you but your posts cannot. Don't wait months before you move.
6) If you're looking for a mobile app, avoid the 'official' app. It's too new and still needs some polish. The best app for iOS is probably Metatext, for Android probably Tusky.
If, after you've created your new Mastodon profile, you are concerned about where Twitter is going you are not the only one. With so much of the security and infrastructure staff gone it's likely that they will be hacked soon. If you had a habit of posting private information in DMs (or are just not comfortable with people having all your tweets in one file), there are automated tools to help you delete stuff on Twitter.
For EU Citizens there are also guides out there that will walk you through how to submit a GDPR data request but I doubt any of the staff that would deal with those processes is still around. It's going to be two weeks at most before Twitter is in serious legal trouble with the EU: Is Elon Musk’s Twitter about to fall out of the GDPR’s one-stop shop? and EU privacy enforcer puts Elon Musk on notice as Twitter melts down