As someone who has tried out Mastodon, Hive, & Post, I will say this right now. Out of all the Twitter Alternatives, Spoutible seems to be the most ideal one & the one site that will actually kill Twitter, I actually made an account & you can register right now. Although it is accepting only 1000 new users an hour cuz of high demand at the moment.

https://spoutible.com/ShiningStar5022