Whatever you get it needs to be upgraded frequently so consider if you really want in in-dash unit. Roads are changing all the time. It is bad enough to have bitching betty send you down the wrong street when you are in a car. Now consider heading down the wrong street in a bus with a toad attached so you cannot back up. Whatever you decide make sure you can install updates.

Also I have found with electronics they are out of date about a week after you buy one, and if something goes wrong with it it is cheaper to puy a new one. If you doubt me pick any electronic device you have that is more than a year old and see if you can get it repaired. Then consider if you can get a drop-in replacement that perfectly fits the hole in your dash.

I'm using a Garmin that also gives traffic reports and it will alter the route automatically to take me around a traffic tie-up. I don't know the model number. Prior to that I was using a Garmin 396 which I could overlay XM radar weather over the route so I could anticipate weather. I used the 396 in the plane and it was neat having aviation weather capability in the bus.