Best Navigation App

I for one love Google Maps and Navigation. When in a city I'm unfamiliar with, it's a life saver. But here's the problem:

Since I plan on switching to Striaght Talk and its apparent limit on data, I need to have a Navigation app that can serve me well so that I'm not drawing on my data reserves.

So, what are some good Navigation apps?

1. Name of app

2. Price (money isn't a factor)

3. How much storage/ space does it require