I'd have to go with the Bruckman firm of Germany, just before the war. Impecable fit and finish, high grade carbon steel, very nice polished horn handles. Post war till the 60's I'd go with the Hen and Rooster. Till the death of the two Bertram brothers, and the sale of the company name, they were probably the best of the post war pocket knives. Really great stag!
In U. S. companies, I'll go with the old days of the Schrade-Walden knives. After the time period they became Schrade, they started a long slow decline in overall quality. But the period of the Waldens were very good!
Of course there is the Opinel company. Theres a heck of alot to be said for a knife company thats been going since 1890, is still family owned, and makes a hell of a good cutting knife for 10 bucks!!!