If you're looking to buy a GPS, then that might be an important question. Although Garmin currently has almost 50% of the market share in the US, Tom Tom is next in line with about 20%. Just so you know, Magellan is third.
Garmin certainly has a wider and deeper product line. They also have the upper end of the market pretty well sewn up. If you're looking for an entry level device, or even a mid priced device, then TomTom certainly is worth considering.
Part of the problem in choosing a GPS unit is understanding what features are offered, and which ones are important to you. Most people aren't interested in the details of how these things work. They're not even interested in fine differences between the two. Most people want their device to work and be reliable, and do everything they need it to do.
With that in mind, let's take a moment and talk about what GPS devices do in the first place.
All GPS's do the following:
There are other standard features, but the above are the main ones.
If you want to pay more, you can get the following:
For an entry level device, a great TomTom GPS unit would be the TomTom One, 3rd. Edition. Right now, they're selling for less than $150. The TomTom One, 3rd Edition does everything an entry level device needs to do, plus has some interesting features. It has real time traffic capability (to help you avoid traffic jams), and has an interesting emergency menu feature. It also comes with free software that will let you download the latest maps, celebrity voices, and other free applications.
Garmin's entry level GPS unit is the Garmin nuvi 200. Right now, it runs about $20 more than the TomTom. It can do everything a basic GPS unit needs to do, but doesn't have some of the bells and whistles the TomTom has. Why does Garmin outsell TomTom in the US? People perceive Garmin as the leader when it comes to quality.
For a mid range unit, you might want to consider the TomTom GO 920, which is currently selling for slightly more than $300. The GO 920 does everything the One, 3rd Edition does, and also includes Bluetooth, spoken street names, a wider screen, and FM transmission capability. (Which means you can hear your unit though your car's stereo system.)
The GO 920 compares to the Gamin nuvi 600's. The Garmin nuvi 660, for instance, sells for essentially the same as the GO 920. Honestly, there's no real difference between the two in terms of big stuff they can do, like Bluetooth or FM transmission. Again, the nuvi 660 outsells the GO 920 because people see Garmin as being the leader in quality. That's not to say the GO 920 is not a very good device. After all TomTom outsells Garmin in Europe, for what that's worth.
So how does a TomTom GPS unit stack up against a Garmin? Both of these companies make excellent products, and, especially in the mid range prices, they are neck to neck as far as features and price. TomTom seems to offer more features at the lower price points.
What you need to do now is browse specific models below and take a look at the current prices.