Most public servers are pretty bad in terms of modern XMPP features [1]. Trust is also a big issue, but one of our goals is to solve this problem by making it much easier to run your own server. We currently default to Dukgo for new registrations but they don't support many of the XEPs required for a good mobile experience (0198, 0313, 0357).

1. https://gultsch.de/compliance.html