What I like about garmin compared to TT. Every tom tom I have tried puts you within a quarter to a half mile of the destination. With the garmins 99% of the time they put you right in front of the building.
Tom Tom leads the pack and is best for Europe, Garmin is the best one for North America, each for the same reason of accuracy and routing.
Some people think all brands of GPS are more or less the same, because they mostly use the same map data. But it's the manner in which they incorporate that data that matters, the type of routing algorithms used, and how the various coordinates are referenced on the map. Garmin leads the pack on that one. All other brands are lagging behind.
Whatever you get I would go for lifetime maps it equels big savings.
Not only savings, but every map update comes with improvements in routing and accuracy, in addition to updating the maps.
I would also recommend lifetime traffic. The traffic often isn't that accurate, because it can change in seconds, but a traffic alert, combined with a CB, can often prevent you from getting stuck in some nasty backups.
As for what I use, I still have my old, ancient Garmin StreetPilot® c550 from 2005 or 2006, with the old style (and less accurate and timely traffic). I keep the maps updated, though, so it stays accurate.
I also use Google Navigator and Google Maps, to find locations that the Garmin cannot find. If nothing else I can locate them on Google and them browse the map on Garmin and have it go there.
I'm looking at upgrading to a unit with a few more bells and whistles. The newest Nuvi 3597 LMT has HD Digital Traffic (real-time updates every 30 seconds, using a number of data points, including the cell phone locations and speed of a gazillion drivers), which is shaping up to be the most accurate traffic/display system yet. It also has a completely overhauled interface which is far superior to the previous models. That's probably the one I'll go with.