I use the one on my iPhone. It works great, gives me turn-by-turn verbal directions with a display, and talks to me through my Bluetooth. Not only that, it has free updates and came with the phone. I have owned both Garmin and TomTom in the past and this is the best so far. So far it has been more accurate. The only down side is that the screen isn't as large as some, but I can get a mount that will hold it in a decent place.
I never use it very long so I don't worry about killing the battery. Also you have to be somewhere that has phone coverage or wi-fi service to start the trip, but after that it tracks off the GPS.
For now I won't waste my time with the others.
