Thought this was interesting from Sarah Ballantyne (aka the paleo mom). Her approach is somewhat shifting to not be so dogmented in paleo, but looking just at the most nutritious food.
The term nutrient density refers to the concentration of nutrients (mainly vitamins and minerals, but also protein, fiber, phytonutrients, and other micronutrients) per calorie of food. High nutrient-density foods supply a wide range of nutrients (or alternatively, high levels of a specific, important nutrient) relative to the calories they contain.
Her Nutrivore Score system is a comprehensive method to quantify the nutrient-density of foods and make the nutritional evaluation of foods objective. It is calculated as the sum of each of 33 nutrients relative to its RDA or AI present in 100 grams of the food, divided by the amount of calories per 100 grams.