I can only speak anecdotally, but I'm on a social slack channel with a group of about a couple dozen or so IRL friends; it's mainly for shooting the shit, but w

I can only speak anecdotally, but I'm on a social slack channel with a group of about a couple dozen or so IRL friends; it's mainly for shooting the shit, but we'll typically plan both small get-togethers and larger many-months-in-advance events through it (although, with our current usage, messages expire much faster than 90 days already, so we'll actually be benefiting from the retention change). I can't really remember why we ended up on slack vs. discord vs. something else (we moved to it from a big group SMS thread ~5 years ago I think), but it's been pretty nice overall, and I certainly prefer it to the friends group which uses facebook events and group chats to stay in touch and organize. At the end of the day, the free tier works well for what it is (IRC with threaded messages, emojis, and a nice mobile app), and if you really care about message retention, you can always write a TOS-violating bot which just scrapes&archives all the messages and host them in like an S3 bucket or something.