As for a true carbon steel blade: simply one of if not the best.
In the right hands and for the right job, I agree, John. Slaughterhouse knives, meat cutters' knives and most knives used in a production process are carbon steel. They require regular steeling (honing) because they don't hold an edge as well as a premium stainless steel blade such as S30V, S35VN or X50CrMoV15, but they aren't as brittle as SS blades so they resist chipping.
Conscientious users who will steel them a few times while they'e in use and will treat them with care when washing and storing will learn to love their CS blades as I love my old Chicago Cutlery Butcher Knife.
EDIT: Added photograph.