This is the million-dollar question, isn't it?
The answer is the usual, dissatisfying, "It depends."
Since each mapping strategy has different advantages and disadvantages, we should resist the urge to define a single strategy as a hard-and-fast global rule for the whole codebase. This goes against our instincts, as it feels untidy to mix patterns within the same code base. But knowingly choosing a pattern that is not the best pattern for a certain job, just to serve our sense of tidiness, is irresponsible, plain and simple.
Also, as software evolves over time, the strategy that was the best for the job yesterday might not still be the best for the job today. Instead of starting with a fixed mapping strategy and keeping it over time – no matter what – we might start with a simple strategy that allows us to quickly evolve the code and later move to a more complex one that helps us to better decouple the layers.
In order to decide...