I've been really impressed with Evil. It's trivial to extend with new keybindings, the code looks very clean, and it even supports text objects.

There's viper mode, which enables vi keybindings. A transitional technology.

You don't even have to ever turn it off!

I once used that. I remember for extra power and/or hilarity I configured it so that emacs commands were all available in vi "insert mode", so that Esc effectively switched between vi and emacs.