Considering that both #XMPP and #Matrix re-invented #decentralized communication while #email was already there, makes #deltachat more interesting.
The fact that DC didn't invent a new protocol for #InstantMessaging and just used the protocol which was already there, and also that how far has it gone, is mind blowing.
At first when I was chatting with @treefit, I already was developing a Matrix client(#chooj) for #KaiOS and it was the only decentralized IM which I was using and investing resources into. I was skeptical but then I thought it would be a good idea to invest into DeltaChat, as well as Matrix. His argument, of course, wasn't good. He was arguing that we need multiple options in the case one of decentralized IMs fail. However this convinced me to give DC a try.
But now, I see that DC has very unique advantages no other messenger has. Their moto is "playing the long term" game. Unlike Matrix which suddenly exploded, DC moves very slowly. As an advantage, DC is much more consistent, hassle free, has less bugs(in my experience) and has better UI/UX than many Matrix clients. But it has got several disadvantages. Matrix has tons more features which DC hasn't got or has added them just recently such as editing messages and reactions. And it is not yet suitable for public groups, like the ones we've got in the Matrix network.
Overall, if you want secure chat with friends or family or other people you trust, DeltaChat is a very good option and the experience is very good. And I haven't seen something like #webxdc in any other IM. However if you want something like #Discord guilds for a community, Matrix is the way to go.
BTW, DC currently lacks funding, thanks to what #Trump did with #OpenTechnologyFund(#OTF). If you can help in anyway, financial or otherwise, it will be extra valuable at this point.
Edit:
BTW, here are websites of webxdc and DC:
https://delta.chat
https://webxdc.org/
Edit2: Make sure to check WebXDC, apps shared in #P2P deltachat groups or DMs.
products preferably.
1/3
CET 
Except Trillian/Pidgin were way more straightforward (no shade to Matrix, it's not really what it's meant for).