Slack has raised our charges by $195k per year

We're using teams in my new company, which is awful for textual communication (lacks threads in chats, groups are more like old forums than new IM). I've been experimenting with self-hosted Mattermost but it seems that it also requires paid license in some situations (e.g. does not have groups for some reason in the free version).

I was unable to find another system. Would anyone recommend me something?

I was considering moving from Slack (free version) to Teams (paid) for a new project starting in October because my workplace already have a license for that. Seems like it will have less features but no 90 day retention annoyances.

You seem to have some experience with both, do you think I am making a bad decision for a ~30 person team?

Others suggested Matrix, but I have a feeling they are implicitly assuming self-hosting. I do think Element works quite well, but I have only used it personally with matrix.org for basic chat, never for work. It does work on both Android and iOS as well as Linux, which is why I use it.

If you're bought into the windows ecosystem its great for shared docs and fine for calls. Terrible as a messenger service

Strongly disagree.

It is NOT a good place to share docs.

Each chat is its own SharePoint, so it is really simple to lose documentation through things getting siloed.

The calls are fine though, and the chat is substandard. A bunch of teams use it for support channels, however there doesn't appear to be a way to join the group for support without being pinged by @channel_name. So you join for support and then you are alerted by everyone else who is looking for support.

At least they have stopped fucking around with "newest on top/bottom", there was A/B testing last year (or maybe the year before) and you couldn't tell which way you had to scroll from one day to the next.