I don't do the butchering anymore, figure I'm old enough to have the right to pass it off to younger ones. But when I did I found putting them in a cone and then just cutting their head off was quicker. As soon as you hang them upside down, they get quiet. And I never just sliced their neck, but took some heavy cutters and cut the head off. No second chance. No undue suffering for the rooster.
I've had 2 roosters actually fight to the death, and the mean one won. We had 24 hens at the time, but the 2 roosters still did not want to share. So I don't keep more than 1, even with 90 hens. So I can pick the nice one. Course I'm after the eggs not the meat. I don't need a rooster at all, but my current one is such a huge gentle grey rooster, that I kept him.