I like Slack but I feel like the have been slow to fix the glaring performance issues. Recently, I will admit, the performance has improved but not sure why it took so long.
However – to be honest I could live without Slack but that is not to say I would go to Microsoft Teams.
Generally I need Google docs, email and some sort of chat but I am not married to Slack.
The level of team collaboration within Slack and across the other product I use is not that high.