My Border Collie is very intuitive and an amazing judge of character. He definitely picks up on my energy... he HATED my sister's old friend who used to hit on me and grossed me out. Same guy tried to alpha roll him, and it was fade on sight.
He's done hold and barks on intruders and uninvited guests. He's just enough to be super intimidating and stop some one, but too much of a puss to really bite. I know he would bite if it was needed, though.
I think a well bred German Shepherd is an amazing, intuitive guardian. My GSD saved my life as a child. He was a very friendly, awesome family pet but would get serious in a second if some one threatened his family. They are the perfect combination of biddable, friendly, and naturally protective for me.
I agree about a well bred Akita being a rarity at this point. My family had an awesome Akita... I've never met one like him, all of the Akitas I know are randomly HA and DA with no warning or reason. A well-bred Akita is AMAZING, but too rare. I would love a nice proper Akita.