My RV (Roadtrek) came with an in-dash radio/GPS that was based on TomTom. Prior to that I always used Garmin. Never could get used to the TomTom, so I replaced the in-dash with a Kenwood DNX571HD that has the Garmin GPS. The Kenwood also does HD radio and I added SirusXM. Much happier now as I have been able to load all my POI files from my old Garmin handheld units.
Map updates on the Kenwood are not free and they're not updated as frequently as they are on pure Garmin GPS units. The Garmin desktop applications like Base Camp for trip planning don't work with the Kenwood/Garmin GPS. The DNX571HD does support both iPhone and Android connections, but the iPhone requires a special cable. There is a USB connection on the rear of the unit that MUST be used for things like POI file installation; the MicroSD slot on the front of the unit only works for map and SW updates, although it is possible to also use it for alternative maps. So when installing the unit it is almost mandatory that one bring the USB port out to the dash with another cable.