It is the most common question when someone is considering veneers or a smile design. The short answer is that it depends; the long one is that it depends on four specific things.
How much tooth remains
This is the main criterion. The amount of healthy tooth structure determines what can be bonded on top and at what thickness.
Colour stability
Ceramic holds its colour more stably. Composite is more prone to staining, especially with coffee, tea, red wine and tobacco, although periodic polishing helps maintain the appearance.
Repairability
A fractured composite veneer can usually be repaired without redoing it completely. A ceramic one normally has to be remade. If there is grinding, this weighs on the decision.
Number of appointments
Composite is worked directly in the mouth. Ceramic is made externally and requires a laboratory phase. That changes the logistics, which matters if you are travelling for treatment.