Openfire vs others: ejabberd, jabberd2, jabberd14

The subject sums it up. Can anyone point me to an objective comparison of the above servers? I need an xmpp server for a public Internet service serving tens of thousands of simultaneous users and I am just getting started evaluating alternatives. Anyone care to compare / contrast the alternatives?

Thanks,

Mark

Its a couple of years out of date, but might be a good starting point.

http://www.saint-andre.com/jabber/jsc/