Re: Vent mounts
I'd like to second that recommendation for the Kenu Airframe+. Anything that will come into contact with the vent or the phone is either rubberized or otherwise made of materials that won't leave scratches and it grips large and heavy phones (Z3v, Note 4, Nexus 6P, etc.) securely and with ease. I do have a couple of things I'd suggest after having used the Airframe and the Airframe+ however. In the center of the Airframe mount, there's a metal rivet kind of thing with the Kenu logo stamped on it. It sits in a depression low enough to not touch the back of the phone, but if you're using the phone naked without a skin or a case, I'd cover that little metal piece up with a piece of tape just in case (I've never really had any issues with that, even with a phone with a curved back like the HTC M7 and M8). Second, the Kenu grips to the vents using that squid leg like design. It rotates depending on the angle you want the phone, as well as how thick your vents are; make sure to test out which position is better before taking your car out on the road (lots of people complaining about a loose grip on the vents don't realize there's a tighter setting). Also, most cars have plastic vent louvers that are connected to each other and to the vent angle control thing by a thin piece of plastic so if you need to adjust the angle of the mount or if you need to put the phone into/ take the phone out of the gripper part, remove the whole Airframe unit before messing with it so you don't break your vents.
It's the cleanest and most discreet mount I've seen to date and I love mine. You just need to take a little care in using it and it'll be fine for years to come.