Garmin 590LM
I've been using Garmin for 11 years now. Currently I'm using the 590LM. If you have a Garmin unit already, they have a great upgrade program for existing owners. If the Sales team doesn't have your model on their list, contact Support--they have a longer (older) list. In my case, I was able to buy a $800 unit for under $500.
The 590 is water resistant and designed as a dual-use for motorcycles and in-vehicle. In the Jeep, I mount it directly above the in-dash GPS. Works well at off-road. I also download/install custom maps for off road use. One of the things I like is the ability to download the track history, study elevation changes, and export to Google Maps or Earth if desired.
The ability to track my route is useful. Combined with Basecamp, doing so lets me create routes for future use. There's a wide range of other features I use as well; of value to the beholder.
While pricey, you get what you pay for with these things. For me, the feature set, water resistance, expandable memory, swappable battery, and app/feature set are worth it. Should last me for 10 years.