If one stays only in the shallow, beginning levels of meditation, then choosing between one or the other can seem to make sense. But if you go deeper in meditation, you will find that both processes are essential
It is very common for teachers of meditation to describe one of two general types of meditation, and to recommend one as being superior to the other:
Concentration: In this approach, one intentionally focuses the attention on only one object, such as breath, mantra, a chakra center, or an internally visualized image.
Mindfulness: In this approach, one does not focus the mind on one object, but rather observes the whole range of passing thoughts, emotions, sensations, or images.