If you are on OSX, I can't stress enough how important it is to swap opt with cmd. Not sure if there's a better one but I use cmdkeyhappy for that.
With the emacs-mac-port by Mitsuharu Yamamoto (available on railwaycat's homebrew tap) you can set this in Emacs with (setq mac-command-modifier 'meta).
True, but it's also very useful to have the same key bindings while using terminal too!