GroupMe is very simple and intuitive. I use it for multiple leagues and therefore they are all in one place/app. You can have individual to individual chats for trade talk as well as group chats for league messaging. Further, I’ve been using it for a few years and it doesn’t appear that chats are removed. I can see what people were talking about month and years ago.
Slack is more complicated. At it’s base, it provides one to one and group chat.
But it also also provides:
-connections third part apps (Google Drive, etc.)
- face to face (may be a payed options)
- a very searchable interface
- and other stuff (I’m not an expert!)
Slack also has these very individual workspaces (one workspace per league). I find it less intuitive or easy to switch from one league to another. This is only a problem if you have a fantasy problem to start off with…
One thing to watch out for in Slack is peoples can join and leave channels as needed. If you don’t notice or understand how this works, you may have people seeing conversations they are not supposed to.