I believed that TomTom is the most popular and searched the net to see if GoodBuy is right. I found this interesting article:
Garmin Ltd. [GRMN] today announced that it is the global leader in portable satellite navigation sales, having sold more personal navigation devices (PNDs) in 2007 than any other manufacturer. The research was provided by Canalys, a leading independent technology market analyst firm.
"Garmin achieved the worldwide number one spot for mobile navigation devices in 2007 by performing consistently well in Europe, more than doubling its shipments on 2006 and increasing its market share, while also retaining its clear lead in the booming U.S. market, which grew to represent 34.7 percent of the total worldwide market in 2007. Garmin had an enviable 47 percent share in the US in 2007, and the market quadrupled in size," said Chris Jones, Canalys vice president and principal analyst.
AP announced the experience of Netherlands-based TomTom, which saw earnings fall 83 per cent in the first quarter, which suggests that the Garmin is the real market leader for stand-alone global positioning systems.
iPhone 3G with GPS capability should be added to the top ten list. It's the best PDA (personal driving assistant) ever made.
iPhone is cute, but it doesn't support integrated GPS navigation functionality. You need to connect to Internet. You can only use Google map service.
I am waiting to get a new release Google phone, a real time GPS navigation gadget.