I have about a dozen GPS units. We buy them for all our trucks. Garmin is the most accurate and with the 'lifetime maps' option is the way to go. Personally I have the DEZL 760 and use it between the RV and SUV. It has three settings, Truck, RV and Car. Enter your weight, width, length in the RV settings and it does a pretty good job of routing. A couple things I've found is that even updating regularly not all streets and bridges are caught. We have a bridge near home that has been replaced, about 8 years ago that is now a heavy weight that used to be restricted. I still get warnings. In other words, PAY ATTENTION!
The only bad thing about the DEZL is that it takes some time to recalculate your course.