Of the following: porcelain, mac, emax, durathin, zirconia, lumineers da vinci which veneer is the strongest and requires the least tooth preparation?

Depends: The names you have mentioned are all brands/types/manufacturers of veneers. They are all good.The real question is which type is best for your specific needs. Consult with your dentist and explain what your desires are. You should be given a variety of options. Choose what's best for you.

It depends: There are many materilsl for veneers that can be very thin and very strong. The choice of materials depends on what your needs are, the reason you are doing the veneers, color, length, spaces. All of these require different kinds of matetials. There is no one material that works for every case. It is best to talk to you dentist about your goals and desires.

Pure Zirconia but...: Probably pure non-layered zirconia can be made the thinest and strongest. However it will be monochromatic and the least esthetic. All veneers can be made resonably thin and strong. The three biggest issues in veneer fracture are an unbalanced bite (dentist corrected), sleep grinding/bruxing ( always wear a nightguard) and biting objects that would fracture natural enamel (duhh!).

Strong veneers: The zirconia is the strongest, but the least esthetic. The bonding strength to the tooth is really more important. As enamel creates the strongest bond, that is the determining factor you and your dentist will use to pick the appropriate material for your veneers.