Digatal or analog servos
It's not necessarily the quality. The big reason is holding power. An 'analog' servo will try to do it's best to maintain the position you're sending it. A 'digital' servo will do everything but get out and push to maintain the position you're sending it. The whole using the word digital as a buzzword is stupid, but effective for marketing => NO less or more effort goes into manufacturing an analog component as opposed to a digital one. They just behave differently.