In my opinion, what is kindest, and most humane is what is quickest. There are many ways to kill something, but whatever ends the animal's suffering (and terror is a kind of suffering) the fastest is best. In my opinion, shooting is the most humane, because it is over so quickly. I have read a lot about the methods of animal euthanasia, and what I have learned is that unless the animal is rendered instantly dead/unconcious, that the animals brain waves are comparable to the patterns of humans undergoing pain, fear, etc., In one study I read, they found that the only way to avoid the pattern of brain waves reflecting the pain/fear parts of the brain was instant deaths that caused destruction of the brain/unconciousness. All of my inquiries have led me to conclude that when dispatching an animal, to avoid unessesary suffering, you should opt for the quickest method if possible.