At the risk of hindering coordination efforts, Pillowfort sounds inadequate to me.
“All reblogs of a post will also be deleted when the original post is deleted by the user”
“While the specifics of what constitutes a bannable offense are complex and covered in our ToS, we can generally say that threatening another user, encouraging suicide, etc. will be grounds for account termination, as will promoting the ideologies of violent hate groups such as Nazism.”
– https://web.archive.org/web/20180420221628/http://pillowfort-io.tumblr.com/faq
“We will also try to come up with a way to lower the barrier to entry for new users, though we don’t want to drop the entry fee entirely because a) we feel that would be unfair to our users who have paid for their registration keys and b) we don’t think our servers could handle a massive influx of new users right now, so we’re going to try to allow as many new users as we can without capsizing the boat.”
Hmm, deletes cascading to reblogs does have a bunch of advantages – less possibility of a post getting out of hand and potentially leading to harassment years down the line, better control over your own content. People who want to add a lot or debate will just need to link to the post in question/quote passages. Or am I missing something?
The suicide thing seems iffy, but I’m willing to wait and see how it’s actually handled. Banning Nazis is good.
Also a sign-up fee is annoying but hopefully will keep the pornbots at bay.
My issue with the sign-up fee isn’t that I have to pay it, it’s that it will limit the site’s user base to only those that are willing and able to pay.
Sure, that’s the downside. Given that it’s a one time fee of $5 I’m hoping that won’t have too big an influence on the userbase’s diversity apart from porn bots and possibly minors (which is sad though).
Other than that, I’m slowly resigning myself to the fact that we’ll always be consumers or product. 
Omphaloskeptomai 