GEORGE WALLACE says: What I think, after more than 40 years involvement with deer and with one very distressing memory of a neck shot that went wrong, is that, in the wild, head or neck shots usually pose unacceptable risks.
The position of the cervical column within the neck changes as the deer turns its head making accurate shot placement problematic.
If your aim is for the brain or top couple of inches of the cervical column, the head itself is very mobile so a sudden slight movement may cause a wayward shot. Such a shot may miss altogether but may equally crease the deer across the head, blow off part of the jaw or damage the oesophagus or windpipe.
Any one of these can lead to a slow and painful death and so will be avoided by responsible stalkers unless circumstances allow the shot to be placed with absolute certainty AND, as in Parks for example, an injured deer can be quickly followed up and dispatched.
When those conditions can be met, my own preference is for a brain shot from the side. The point of aim is through the base of the ear, not below the ear which will cause the brain to be missed.
If the animal is facing away, place the bullet through the atlas / axis joint into the brain.
From in front the brain is protected by heavy bone which can cause the bullet to ricochet and just below that is the mouth full of very hard teeth which can also cause a bullet to behave unpredictably.
Just under the chin is the best spot when the deer is looking straight at you. But you must then take care that the bullet does not go on to damage valuable meat.
In summary, you really cannot beat the good old heart / lung shot for a humane and certain kill without unnecessary meat damage.