Frozen veggies are healthier and cheaper. Plus you get to cook them to your taste, rather than what the canner decides (cooking too long, adding salts, etc.)
Frozen veggies definitely win if you have access to refrigeration -> access to energy. Canning is a revolutionary preservation technique in that it allows for long-term storage of perishables at room temperature.
http://www.heathernicholds.com/nutrition/frozen-vs-canned-ve...