@Shamar @alcinnz @rysiek @MatejLach @varx
Also, different users have different level of expertise, and need different level of features. Eg. I think Conversations is a way better XMPP client for newbies than Gajim, but if you're an XEP-reading nerd debugging the protocol, Gajim is way better suited.
Finally, I think that keyboard with good keybindings beats down mouse or touch input wrt. speed & precision, and touch UIs need different design than kbd or kbd+mouse ones (eg. smaller buttons).