I use a Garmin 855 with a ball mounted zip up rain proof padded cover with a window. Plug it into the front of the radio & into the lighter in the dash.
I have about 1500 mp3's loaded & 200 Audible books & the gps instructions come through the intercom also. I can also do a bluetooth with my cell if I want.
I thought it might have a problem one day so I bought another one off EBay. It goes in the luggage if ever needed. Most of the time I have forgotten to throw it in.
All total I have under $250. It has a bunch of miles on both the motorcycle & in the vehicle. Many hours without a blip of a problem.
As Screwball said, you always can move the screen to get rid of glare. Really if you need to check much on the screen, you need to pull over & do that anyway. The only thing it doesn't do is interchanges & traffic, but I have found out how to read signs. LOL !
I just really don't care if the screen says Harley Davidson when it comes on.