I find waze to be superior to other options when trying to find the quickest or shortest route. It uses data from its users to determine slowdowns and I have learned shortcuts even close to home. Waze has probably saved me hours of my life, both in fewer hours on the road and less stress. It is best, for me, when dealing with traffic in cities.
That being said, I don't NEED a GPS, I just find it to be a handy tool. Just like a hammer. I could use a piece of angle iron, rock, or some such to pound a nail, the hammer is just more efficient.