I'll be the dissenting voice on the Garmin RV760. I have this one plus to other Nuvis and I find the routing on the RV760 can be just plain wonky at times,not at all as reliable as the other devices.
I now run Waze at the same time as a bit of a second opinion and try to check the routing before setting out. Last trip out rather than set the RV760 to "fastest route" or "shortest route" I chose another option the name of which escapes me now, but may have been most fuel efficient route, and the device chose a routing that was very similar to what Google Maps was suggesting.
I've spoken with Garmin but got no real answers other than re-install the maps, which I did. Plus I continue to make sure everything it up to date.
Would I buy the RV760 again? Maybe, maybe not. I could always use Google Maps with the lowclearances.com database installed. But then again, there are other nice features on the RV760.