Neck shot= small movable target area, which is further away from the ground, thus more difficult for a good backstop. If you get it right beast drops on the spot. Get it wrong, beast goes down, then gets up and runs of with a hole through its wind pipe or through the neck muscle that is not immediatly fatal.
Chest shot = 6" diameter target and generally much safer - closer to ground so good backstop. If you go just under half way up tight in behind the shoulder , if go a bit back you still take out the lungs and liver and cause massive blood loss, if you go a bit high, you take out the spine, if you go a bit forward, yes the bullet will smash the shoulder, but plenty of damage to the heart and lungs, and if you go a bit low you take out the heart. All produce fatal damage and the beast will die very quickly.
And **** happens - I shot a buck last week at very last light - the bullet hit a piece of dead cow parsly stalk - just before hitting the target. This knocked the bullet of course and it went three inches to the right smashing the top of the nearside shoulder, straight through the heart and lungs and out of the offside shoulder. Beast dropped and then ran 30 yards through a fence before pilling up dead. Heart and lungs look as if they had been through a mincer when I gralloched it - bits of bone every where and I scrapped both shoulders.
So I would stick with chest shots. I have head and neck shot a lot of hinds when I was younger and stupider, enough to know that sooner or later it goes wrong, and they can run a very long way.