Usage of Sling Model

[akash_gupta2]

Which one of the following a better way of defining a sling model and why?

@Model(adaptables=Resource.class) 
public interface MyModel { 
     @Inject 
     String getPropertyName(); 
}

      OR

@Model(adaptables=Resource.class)
public class MyModel { 
     @@Inject
     private String propertyName; 
}

Can you tell me a defined use case for using an interface as a model when all the methods are to be overridden in all the implementation classes?