Finally!!! 

This is the best if found at holding a phone that actually works as it's supposed to. 

I didn't try the dash/windshield mount because I didn't want a view obstruction but the vent clamp/mount is perfect. 

It has a small upturned lip that catches the back of the vent and a tightening screw to clamp the jaws shut. 

Easy on/off and rotates to your liking. 

Seems very well made and thought out.