Legit just chose mas.to because, at the time of my signing up, it had open signup. I have been absurdly lucky to land on a largish public instance that is impeccably maintained and diligently moderated. (It no longer has open signup because that was causing problems for others and it has a diligent, responsive mod team that considered the effects of their actions! But I think I can generate invites, if you're tempted.)