You're correct that most came from the Atlantic region of France - particularly the area north of the Loire, especially Normandy, Poitou, and the Paris/Île-de-France region. This map should give you a rough idea of the distribution:

http://www.axl.cefan.ulaval.ca/francophonie/Nlle-France-prov-peuplement.htm

A disproportionate share came from Normandy - such quintessentially Québecois surnames such as Tremblay, Gagnon, Côté et Gagné are all distinctively Norman in origin. These origins are also reflected in the fact that Québecois and especially Acadian French retains certain maritime expressions that would have been more common on the Atlantic coast of France (e.g., "amarrer", "gaboter").

Also, the migrants who came to New France tended to come from urban areas, even though the great majority of French people still lived in rural places in the 17th and 18th centuries. About half of all male migrants and about 70% of female migrants came from urban areas.

For more information, see Hubert Charbonneau and André Guillemette, "Provinces et habitats d'origine des pionniers de la vallée laurentienne"; Leslie Choquette, Frenchmen into Peasants : Modernity and Tradition in the Peopling of French Canada.