As someone who has been on Discord since the beginning, runs Discord communities and writes Discord bots, here's my list of three things that I believe would make a viable Discord competitor:
- Free without requiring self-hosting;
- Absolutely frictionless community access - here's an invite link, you can start chatting immediately;
- High quality voice calls with screen sharing.
I don't think there is a competitor that hits all three points right now. Screen sharing in particular is often disregarded by developers who have limited interaction with Discord and don't truly understand the platform. It was not an original feature, but it is Discord's killer feature. Because screen sharing is also impromptu videogame streaming.
I feel like this isn't just business services though.
American engineers are used to working for either big tech or "Silicon Valley inc." European engineers are used to working for Volkswagen, Ikea or Ryanair. Very different kinds of businesses who treat tech very differently.
Over here, competing on user experience and attracting users with a slick interface that people love to use isn't really something most companies think about (and so they get their lunch eaten by the Americans).
Nowhere is the European mentality more evident than in cybersecurity, where outdated beliefs still dominate. In this mentality, everybody is out to get you (and that notably incudes your vendors, your business partners and your customers), so all infrastructure has to be on prem, open source is free and hence suspicious by definition, obscurity is the best kind of security, encryption doesn't work so data should go over custom fiber, and if you have to expose an API on the public internet, an Authorization header isn't enough, it should also require MTLS behind a layer of IpSec.
I'm an European engineer and I can confirm that our tech is often broken and customer-reachable people are usually obtuse and hostile about it. We don't even seem to properly implement our own legal requirements. Sometimes, Americans implement the RGPD better than we do.