Waze app on the phone supplemented by an older Garmin GPS.
When they disagree, I'll have my wife open INRIX App on my phone to determine why they disagree. It is often that one is picking up a traffic situation before the other one. Sometime they just calculate routing differently. Generally, I know my routing ahead of time by using Google maps on my computer.
Funny story on a bad traffic situation caused by a multi car pileup. I wasn't towing at the time. Both GPS and Waze told me to get off at an exit that made zero sense... so i did. Ran into an epic traffic jam of everybody else getting off at the same exit. Stuck behind this over size load. So, I continued to reroute using the soft stuff between the ears now. Get back to the original reroute, and turned onto the road right in front of the over size load, literally gained nothing. Get back on the original route, right in front of a highly decorated and colorful semi, that stayed on the original route. It was eye opening... but I was a lot less frustrated :)