That's a hard question to answer because to me, their albums fall into a couple of different categories - studio, experimental and live and I like all three for various reasons. They were more known for their live recordings but if you're not familiar with them at all, I'd suggest American Beauty and Workingman's Dead. Not my favorites but just to give you an introduction. I tend to listen to their live albums which I would highly recommend Europe 72, Live Dead and One From The Vault and Two From the Vault.