I originally used a cheap $7 one from Amazon that was great, magnet power and size wise! Except it wasn't long enough for me to be able to touch the screen with my hand still on the wheel.
So I spent a lot more money and went with a
67 Designs one. Diamond Plate base, Mini Arm, and a G2 Magnetic pad. The Mini Arm was tool long so I ordered a Nano. Perfect... Until I started driving and my iPhone7 would just slide off.
G2 Magnet:
The magnet isn't near strong enough.
So unfortunately I had to reorder, again, a G3 magnetic pad. This finally worked and is a nice looking set-up, IMO.
G3 Magnet:
If buying something for your phone or MAYBE a mini iPad, do not consider the G2. I honestly don't know what it could hold unless rotated near flat, maybe.