I've been using ejabberd for a while, but it's painful. It has an
extra daemon
process used for mysterious Erlang stuff, it binds to more ports than it should, and it doesn't work without a lot of fiddling.
I'd like a simple jabber server that uses plain text files to tell it the IP address to bind to and the valid user-names and to have a simple utility for generating passwords like the htpasswd program that comes with Apache.
Getting Apache going is MUCH easier than getting ejabberd going, but Apache is a much more complex program.
Back in the days of Debian/Lenny I investigated all the options and determined that ejabberd was best. I may have been wrong then, but even if I was right there is scope for other programs to have been improved.
ejabberd was the only one I found that I could get working with psi and supported an msn gateway. Now with my iPhone I've only found one 'proper'[1] xmpp client that also works with the msn gateway. If you do find one that meets your expectations please do share it here! James [1] where 'proper' means that the iPhone logs into my server rather than sending my username and password to a third party server which then logs into my server.