For larger birds i use a hatchet. Less chances of messing it up. For small birds i use a club to the head. It's instant for small birds. I've never messed it up that way.
I've been interested in this very subject for a while now and after several different combinations I've found one i like and want to go forward with. I call it a mayhoubin. It's from a cross between a black breasted red malay and a silver spangled appenzelar spitzhiuben.