I use the native OSX emacs in the terminal with the fonts increased a fair bit. It loads really fast (~ 1 second) I tried Aquamacs but didn't like the fact that it was significantly slower when starting. I'm a new emacs user so I don't really see the need for all the bells and whistles the larger packages tend to offer. If I need anything I just install it from emacswiki.org. Also I found dotfiles.com quite useful for customising my setup.