Note 1: for anybody interested in joining XMPP, even just for trying, Disroot.org community is probably the best provider available, in terms of privacy, reliability, security, supported XEP extensions....and being located in Netherlands offers close to none latency to European users.
Recommended alternatives: 404.city, SDF.org, Neko IM, jabber.at, blabber.im
Note 2: The best client for Android instead is undeniably Conversations, possibly under every single aspect, although I personally use the Pix-Art Messenger fork; Yaxim is decent too.
Movim is a fully-featured browser frontend.
The best CLI clients are in order profanity, poezio, and centerim; they're all widely available on *BSD; unfortunately, as of today, none of them supports OMEMO (profanity an experimental plugin), so , when in need for encryption, one has to fallback to either OpenPGP or LibOTR