I vote for Magellan GPS units.

Reasons why:

1. It talks back to you when you type
2. The keyboard is much less errorprone than either the Garmin or TomTom
3. Simple to use.

Negatives:

1. Does not start navigation instructions unless you are on a road that it recognizes on its internal map. If you are in the middle of a forest somewhere on a road that GPS doesn't know, it will not start navigating for you.