As a Vim user, I've always been drawn toward using vi keybindings in bash.

However, as a Mac user, all of the Cocoa text widgets more or less support emacs keybindings, so having a working knowledge of basic emacs movement commands has been very useful.

The emacs bash/readline keybindings also have a really neat trick that the vi bindings don't -- keyboard macros!

Ctrl-( to start recording, Ctrl-) to stop, and Ctrl-x to execute.