Another factor to consider when determining how to pick the best GPS to buy is the map accuracy. All GPS units have to get their maps from somewhere, and depending on the manufacturer of a given GPS, the maps will come from either TeleAtlas or Navteq. Some people suggest that Navteq provides more accurate maps, at least in the United States, but the difference between the two is most likely very small. Fortunately, if you have a destination in mind that you plan on using your GPS unit at, you can check that destination at either Google or Yahoo maps. Google Maps use TeleAtlas, and Yahoo Maps use Navteq, which makes it easy to compare the accuracy of a given area between the two. TomTom GPS units are the primary user of TeleAtlas maps, while Garmin and most other GPS manufacturers use Navteq.