For proffesional use a TT GO950 Live with Live Service. So I never get stuck in traffic ( I hope :D ). Also very handy as an extra carkit.
As an alternative I have a Smasung Tab with TomTom, iGO truck, Garmin, Navigon, Here and Sygic. Why six???? Just because it's possible. :D

And if everything fails, there is always an old Nokia phone with ovi maps.