Building Slack alternative

Thinking of building a collaboration platform as a side project. Kinda like slack. If you were me, how would you folks start? What stack would you prefer?

We use 1. Freshdesk 2. Mixpanel 3. Gecko boards 4. Jira 5. Slack

The new features in slack really makes it one and only place to do your everyday tasks. You can connect with your colleagues You can do a huddle, can share shreen too You can create canvas which is basically like a confluence page You can even create boards in canvas to track your tasks and many more Somewhere or other i feel that if atlassian do that, they'll have a great advantage over the competition, because many companies already use their products

What do you folks prefer from a communication perspective. I've been using Teams extensively but want to know more about folks who've used slack or both....what's your opinion.

It's been almost a month at my new job and among other things, the transition from email to slack for internal conversations has been very very interesting. previously everything had to be on email for it to be considered legit, slack was also there but not an official channel. now it is slack and only slack, personally prefer this.