We use Openfire, after running eJabberd for a while and having too many issues (I actually learnt some Erlang just to fix one of the bugs).

We have two uses. 1. Web based per-page chat for all our logged in users, then using Candy+ejabberd/openfire, but now using a custom node socket based chat server. 2. Internal chat still on Openfire. Have thought of checking out Zulip/Mattermost et al.

Never tried Prosody, and feel that xmpp never got the client thing quite right.