The most beautiful crown for a tooth is, without question, all-porcelain or all-ceramic. With porcelain fused to metal crowns, there has to be an opaque layer put over the metal to block out its color. This makes it impossible to have a translucent restoration that mimics the translucency of natural teeth. Only with pure porcelain or pure ceramic can you have such translucency.
To define some terminology, porcelain is a particular type of ceramic that is built by stacking and firing. When we say ceramic, we include porcelain—porcelain is a type of ceramic. All porcelain crowns are translucent, and their color is influenced by the color of the underlying teeth.
There are several factors that go into the selection of crown material: strength requirements, esthetic requirements, and the abrasiveness of the material against the opposing teeth. There is not a single crown that is clearly superior for all situations. We have several types that we use, each for different situations. We commonly use all zirconia, porcelain fused to zirconia, e-max (lithium disilicate) and porcelain-fused to metal crowns.