im sorry but Google Maps on Android destroys TomTom/Navigon out of the water. And now with vector support, offline cache mode, and better UI overhaul, its now even better.
EDIT: I don't think you've used 'Navigation' on Android. Its by far a superior navigation application than TomTom/Magellan. Hands down.
Haha, no. TomTom and Navigon are much better. Google Maps obviously gives you more bang for your buck seeing as it's free, but you'd have to be endlessly daft to compare it to TomTom or Navigon.