Kerrygold is from grass fed cows and a lot of people on here recommend it. My personal favorite (also grass fed) is called Smjor from Iceland, but Whole Foods Market is the only retailer that sells it in the states. I like it because it has a lower water content than other butters so you're getting more what you pay for. Also it crisps things better (salmon skin anyone?), and it can take a higher heat than other butters without scorching.