GPS units vary significantly by category and by capability within each category. All-purpose devices are good for a broad range of uses but devices targeted to specific applications are usually better within their specific realms. Though devices can be used for purposes other than those intended, you should shop for GPS units designed for the specific applications for which you are most likely to use them (an automotive GPS device for driving and a handheld device for hiking).
Within each product category, you will find entry-level models and more sophisticated models with enhanced capabilities. For most of a product category, accuracies will be relatively uniform but high-end models may make use of DGPS and advanced signal-processing for increased accuracy. High-end models will also usually have specialized or expanded features that make them better suited for their intended applications than models on the low end.
High-end automotive GPS units will often have greater and more detailed map coverage, advanced signal-processing to reduce errors, enhanced voice-command navigation, touch screens, and more extensive points of interest (like gas stations). High-end units designed for use in the wilderness will often have topographical maps, a compass, a barometer, an altimeter, weather reports, an emergency beacon, and two-way communications. Paying more for a GPS device is often well worth it.
The Top Manufacturers of GPS Units
The general consensus among GPS users (and this is reflected in the marketplace) is that the top two manufacturers of GPS devices are Magellan and Garmin. Both companies have experience that stretches back to the early days of the Global Positioning System, and accomplishments that allow each to argue their superiority. There are a number of smaller GPS providers that can be included as players in the GPS world but none that can rival the top two in the consumer GPS arena.
