MacVim works well and certainly looks more
mature than Vim-Cocoa, moreover there is a Cocoa plugin
architecture in the pipeline for MacVim (and someone is already
working on a TextMate style file browser tray plugin which is a
huge ++ IMHO).
Aquamacs is very usable and looks pretty good.
Supports both traditional Mac OS style keyboard shortcuts
(command-O, command-S) and the Control/Meta shortcuts for those
raised on traditional Emacs. It is definitely more Mac-like than
Carbon Emacs. It seems stable and fast, but I am not an Emacs guru
so I don't stress it all that much when I use it. I can't speak to
the extensiveness of the included elisp packages, either.
GNU Emacs for OSX can be found at emacsformacosx.com. In addition to the
latest stable release, there are also pre-release test builds and
nightly builds, and Atom feeds are provided for tracking all three