Most phone holders require 2 hands to attach the phone, some work with one, but the magnetic one I have is by far the easiest to attach and detach the phone. Can place the phone on the holder while holding it with 2 fingers, and it doesnt require any fiddling or to be precise as to where place it.
Even the suction system the op mentioned in the other thread requires fiddling and force to attach/detach it.