I vote Google Nav. A few days ago I would have voted TeleNav, but I had some time to play with Google Nav today while my wife was driving. It doesn't necessarily have the layout like a Garmin as wyelkins mentioned (although it DOES show your ETA in the lower left corner.)
What I like WAY more about Google Nav is:
-Satellite View
-Street View
-Ability to turn "Compass Mode" on in Street View, letting you move around physically and see the street view based on where you're actually facing!
-Integration with Google Places... Looking up restaurants, etc shows actual reviews, menus, hours, one-click calling, etc. Much more interactive and content-rich (real-time).
I don't really see any features missing in Google Nav that I've been accustomed to with my Garmin, or especially with TeleNav. Once you get a feel for it, it's an amazing app IMO.