I'm extremely pleased with GNU Emacs 23.0.60.2 running on Ubuntu
Linux, but I'm going to be doing some development on OSX, so I'm
soliciting opinions regarding the best GNU Emacs for that platform.

I've come across Carbon Emacs and Aquamacs Emacs which seem pretty
good, so I doubt that it's worth compiling v23 from source to run
under X11, but it would be nice if I could use my .emacs from Ubuntu
as is.

Being closer to the GNU Emacs environment I'm used to is more
important than tight integration with OSX to me. Nice fonts are
important also. I had to put in some work to get them on Ubuntu
(apparently v23 is necessary):

http://lojic.com/blog/2008/02/07/nice-fonts-for-gnu-emacs-on-ubuntu-linux/

Thanks,
Brian