GPS and Navigation Software

I bought a new GPS bluetooth navigation system (Navman 4410) about 6 months back. Now after using it for a while I'm realizing there are differences in the quality of Map data that the GPS software uses. The Navman GPS I have uses map data from Teleatlas. Most other popular GPS vendors use map data from NAVTEQ. Navteq has a sort of monopoly in this area. So they charge a premium. Even google maps uses data from NAVTEQ.

For a brief period of time I used HP's iPAQ Navigation System before I returned it. HP's hardware was based on older chipset while NAVMAN's is based on newer chipset which had more powerful antenna and could lock onto more sattellites easily. I went with NAVMAN for this reason. But I am now realizing that the quality of map data is as much important as the quality of hardware.
Given a chance to shop for a Bluetooth GPS again, I would go with a GPS vendor that has NAVTEQ maps.

To illustrate the difference between Teleatlas and NAVTEQ take an example of the directions and instructions that NAVMAN GPS showed when we were going to Seattle. For some interstate highways it won't display the name of the highway, just say 'take a right turn in 34 miles'. That is not very helpful. On the other hand NAVTEQ maps also have information about the exit and entry ramps to the freeways and would show the NAME of the exit ramp. For example, it would show 'Exit 292 Ramp' for the section of the road near I-5 where we take an exit on I-5 to go towards beaverton on 217. That's very nice!
Another quirk of NAVMAN software is that its ETA estimates are based on traffic speeds in New Zealand (that's where they are based in). So it was showing it would take almost 4 hours to reach seattle from our house when we actually reached there in 3!!!
Next time I buy a GPS device again I'll make sure it has NAVTEQ maps.