Organic milk is better for you:
PLOS ONE: Organic Production Enhances Milk Nutritional Quality by Shifting Fatty Acid Composition: A United States?Wide, 18-Month Study
Those who drink a lot of milk, especially high fat dieters, might have a look at this. I would assume that the same fat ratios will apply to organic butter. I can sure tell it when my local organic dairy puts the cows out on grass in the spring. Tastes delicious.