The most worthy of leading the prayer

Who is the most worthy of leading the [congregational] prayer; is it the young child who has not yet reached puberty – but has memorised half of the Qur.aan, or a man who has only memorised 5 chapters [of the Qur.aan], as well as being upon the Sunnah, and [of sound] ‘aqeedah, and possessing knowledge of hadeeth and fiqh; and may Allaah reward you?