Zirconium crowns

Undoubtedly the best that modern dentistry has to offer at the moment

Stronger and more sustainable
Biocompatibility
No allergic reactions
No gum discoloration caused by oxidation of the metal component
More aesthetic as the zirconia skeleton can be colored in 16 different shades
Absence of hypersensitivity - teeth do not react to large temperature amplitudes in hot and cold
Zirconia crowns are gentle on the teeth because their filing is minimal and there is no need to kill the nerve of the tooth.
With monolithic zirconia crowns there is no danger of breaking off pieces of ceramics from their surface. This issue exists with metal-ceramic crowns.