The list is unfair to Emacs -- do you mean XEmacs, GNU Emacs, MicroEmacs ...
I vote for FSF GNU Emacs 21.3, and that edition specifically. 21.3 has changed the way I do my computing, it has changed the way I use my desktop and revolutionized the way I communicate ... and I'm a long-time Emacs/XEmacs user!
Allow me to explain: True, all Emacsen let you integrate your email, newsgroups, rss aggregator, irc, telnet, command shell, directory edit, programming environments, xml and text editors together in a unified whole where any part of any of those can quickly move into any of the others. That's something we Emacsers already know. And XEmacs set the standard for I18n and the merging of graphics into the otherwise scary-text buffer panel of a traditional Emacs. GNU Emacs 21.3 does all of that too.
But ... what it also does is such a small thing that it's hard to say in a what that conveys the true importance, and what's worse, it does two such under-the-hood things that are independent of each other, but combine for a one-two KO.
1. Not in any distro that I know, but the CVS of Emacs 21.3 towards the end of 2004 introduced the --with-x-toolkit=gtk option ... suddenly I have the power of Emacs integrated and consistent with the rest of my (ICEwm) Gnome desktop! I've been waiting hundreds of years for this! Tear-off menus, scrollbars consistent with every other, Gnome themeable windows ... it's really hard to describe the bliss
2) here's where it knocks XEmacs off the map: GNU Emacs 21.3 can now reliably run concurrent processes. XE has some abilities in this, but tends to crash these external forks and in XE any crash means a total application GUI lockout. GNU Emacs is steady as Gibraltar.
The combination of both these new-for-2004 innovations in the stalwart old TWENTY-YEAR-OLD desktop environment is ideal for merging with the Mozilla Mozex-plugin to let me edit text-areas in a REAL editor, and coupled with new 3rd-party Emacs innovations like emacs-w3m and riece has given me a completely integrated and seamless digital communications environment.
That's new for 2004, unparallelled by any of the other editors, and hey, the old girl's worth an award now and then y'know