Funny, I recently posted in another forum about this. I use this. The I.TEk Universal Phone Mount
It is heavy and thus does not slide across the dashboard.
It holds my Galaxy Note Edge with a case very well in landscaped. It also holds my 6.3" Mega without a case too.
The upper lid acts like a shade to reduce glare but one can place a index card if need be to really have a shade.
It has a silicone pad on the bottom to really grip on to the dashboard (but I didn't take the tape off of it so I can move it around)
The bottom portion of the unit is like a bean bag and really doesn't move even on these potholed streets of NYC.
When not placing a phone or gps unit in it, it is small and streamlined enough to look like it is part of your vehicle i you leave it on the dashboard.
Another good one is the Celgo gooseneck that is long and flexible enough to curve to the contour of your dash.
TS