My answer to this question is : It depends. The advantages of dry dog foods is that they are less expensive,and they have an abrasive effect on the teeth,which promotes healthier teeth and gums. Dry foods have some disadvantages; they are less palatable, are less digestible, and have a shorter shelf life. You can add water to make them taste better to the dog, by adding 1 cup of water to 4 cups of dry food( Don't leave moistened dry food down as it will get sour), but then you lose the beneficial effect on the teeth and gums. Another disadvantage is that only dry ingredients can be used in formulations. Drying ingredients reduces the digestibilty and nutrient content. Because of packaging, the amount of fat that can be added is restricted. Dry dog foods are lower in essential fatty acids. Also dry dog foods have less shelf life. Dry dog foods should be purchased from an outlet that has a high turnover and don't purchase more than a one month supply.
Canned foods on the other hand are more palatable and digestible but are more expensive. 75% of canned foods are water, while dry foods are about 8%. The good news is that in high quality diets produced by major manufacturers, the loss of nutrient content due to processing has been adjusted for. However, it really depends on the dog you are feeding and if it has demanding nutritional requirements like a hard working bird dog that you can't keep weight on or a lactating bitch. You can increase the nutritional content and digestibility with a smaller volume of food. Some animals with extreme nutritional demands simply cannot meet those demands with commercially available dry foods.
I feed my dogs a high quality dry food and add canned food to those dogs that need it, when they need it. I feed a canned food at times during hunting trips.