Garmin Dezl 760 here. I had the first RM 5" rv gps and it was ok. Screen was a little dim and the touch screen was difficult to use but I got rid of it when it quit communicating with my computer and I couldn't update it. Spent over an hour on the phone with RM tech with no solution.
The Dezl has an auxiliary video input but I don't use it. It does communicate with my cell phone via blue tooth and allows hands free cell phone calls and also will use the phone to display a weather map.
From my experience, Garmin has the best display but I may be biased because I keep comparing it to my older units and I'm sure all the manufactures have upgraded their screens.
I use the POI Factory website to download extra POI's to the Garmin.