“What type of crown lasts the longest?”

Nothing is forever, most crowns are very strong, but many others factors play important role, like if patient is grinding his teeth, small tooth holding the crown and so on. Trust your dentist

It depends on how you take care of it, your diet and how you use your teeth. The longest lasting crown is still a solid gold one! Gold happens to have a similar expansion/contraction rate ( modulus of elasticity) as tooth structure. All other materials are much more different.

There are many factors that affect the type of crown placed on teeth. Anterior (Front) teeth require different crown materials from posterior (back) teeth. There are many reasons, but the 2 main ones are; 1- we have to asses the pressure those crowns will be under, 2- Aesthetics to make sure that crown looks like your other natural teeth and not an odd tooth that sticks out in every photo taken. That being said, the answer to your question is there isn't one specific type of crown that lasts the longest, it depends on the location of the tooth, the pressure placed on that tooth, and an evaluation of your bite (occlusion) and how your teeth come together. 

Alexander Moqattash, DDS

Full zirconia crown

The dental crown with highest strength is zirconia crown or zirconia veneer, since they are the strongest. However it is not for everybody, depending on the color and your bite. Any crown such as Emax , or pfm can last a long time, if it was done right, and you do great oral hygiene. for more information on zerconia crowns or veneers click here: https://celebritydentist.com/zirconia-veneers/

Without question gold crowns have the best history of longevity. However, the newest zirconia crowns have not been in use as long and may have equal longevity.
Beyond type of crown the most important factor is not material but careful clinical processes performed to restore the tooth with a crown.
A dental crown, in most cases, is not a product that the patient buys. Rather, it is a method of restoration of a damaged tooth to provide continued service to the patient.
Probably, skilled execution of the process is more important than the material type.