I tell everyone about Kerrygold which is sold cheapest at Costco. It tastes amazing, is 100% organic and grass-fed boasting high Vit D and A. I love roasting or sauteing veggies with Kerrygold. Or brown a bit of butter to put over asparagus. Nothing makes veggies taste better than butter.
Update: since Kerrygold is madly popular, supply and demand has made it cost prohibitive, at least for my family. I also recommend Organic Valley Pastured Butter and Vital Farms Pature-Raised butter.