All settings are tools. If subjects or I are in motion, I need shutter priority. If DOF is vital, I need aperture priority. If light is tricky, I use full manual. If I just want to make sure I get a shot, I use auto. With some PNS digicams, I'll let them try to outsmart me. That's usually not too hard.
That said, I'm usually on some form of aperture priority, even with a totally manual VF folder -- there, instead of relying on the cam's programmed responses, it's my brain (conscious or otherwise) that's doing the prioritizing. With a manual lens on a smart cam, or less-than-perfect light with any cam, aperture always trumps.
Familiarity breeds - Cleanliness is next - A penny saved is a penny