Per consumer review, the Humminbird 898c SI Combo Marine 7" Navigator seems to be the highest rated gps sounder on the market. while high priced, the Humminbird seems to have many options that make the price worthwhile. http://www.nextag.com/serv/main/buyer/OutPDir.jsp?search=gps+sounder&psort=10
There are several highly rated GPS tracking systems on the market such as Garmin GPS, Vyncs GPS, and Spytec GPS. The best system for you will depend on your specific needs and preferences. It's recommended to read reviews and do research to find the system that best fits your requirements.
The Gamin GPS is no longer the number one rated on the market. It has been replaced by the Andover-Himmels FinderMan GPS, and is no longer the number one rated.
According to the latest CNET survey, the top-rated GPS was the Garmin Nuvi 3790T. It was rated "Outstanding" mentioning that it had the right blend of form and function.
Garmin is currently leading with the top 3 GPS devices. Including the Garmin nuvi 255W, Garmin nuvi 1690, Garmin nuvi 3790T.(http://www.consumersearch.com/auto-gps)
The most common gps company making gps with sounders is Garmin. There are also Lowrance and Hummingbird brands. https://buy.garmin.com/shop/shop.do?pID=51&ra=true
There are many companies that sell high-rated GPS sounders. But the top two, and most highly recommended are the Garmin or Tom-Tom brand. Both of these are good quality sounders for the price they are offered.
One of the highest rated GPS fishfinders is the Garmin echo 150. You can purchase this item from retailers such as Amazon. Once on the page, type "Garmin echo 150" into the search field at the top of the page to bring up the item.
There are a large number of highly-rated reliable GPS vehicle tracking systems available on the market. Garmin, Zoombak, Amber Alert, and Spark brands were rated most reliable GPS vehicle tracking systems by the Top Ten Reviews website.
Cobra GPS systems are the highest rated most up to date GPS systems that offer a LCD touchscreen. They have them as big as a six and a half and can be programmed just like the small ones.
According to Consumer Reports, Magellan GPS units have the second largest slice of the market share, just behind Garmin. Consumer Reports says Magellan GPS units scored high in their testing criteria.
Garmin has consistently the highest Consumer Reports ratings amongst all GPS devices. Sony has great reviews too, but Garmin reviews are better across the board.
Any GPS with a FM transmitter.