I don't know if it is the best, but I really like mine.

You can set up addresses or waypoints, and route to them, set up a route by selecting a point on the map, find nearby restaurants, hotels, and gas stations, etc etc.

The only downside is that you have to load the unit from maps kept on a PC. I bought a 256MB memory card, and that allows you to keep quite a bit pre-loaded. I would advise buying the largest memory card available, so you can load up lots of map area to the iQ3600