I've used the Rand McNally/Magellan for abot 4 months and find it servicable. It takes me the way I'd like to go more than 90% of the time but it has lapses. I haven't met one that doesn't. Google, Waze, and Garmin have all led me astray from time to time.
I've learned to look at the map and compare it to the GPS route before I leave. Fortunately, my better half is pretty diligent about this. And we travel with paper maps just in case the GPS gets confused.