Similar to any other medium, Discord Servers for nieche interests where there is an incentive to go back (semi regular events / activities) are better than anything else mentioned above.
What makes discord better medium
- Ability to have single / threaded chats
- Multiple channels (#general #help #more-nieche)
- Instant transition between voice and text channels
- Able to screencast (watch content together, explain understand better)
- Stimulating being together, not necessarily talking (music channels, work together channels)