what takes precedence - learning nach or learning mishnayos?

Darshening the pasuk “v’etna lecha es luchos ha’even v’hatorah v’hamitzvah asher kasavti l’horosam”, the gemara (Brachos 5) explains that luchos refers to the actual luchos, torah refers to mikra, mitzvah refers to mishna, and kasavti l’horosam refers to nevi’im and ketuvim. Achronim point out that the derasha does not follow chronological order in which these books were written, but gives precedence to mishna over nac”h. In the gemara’s discussion (Kiddushin 30a) of the scope of the chiyuv of talmud torah upon a father must teach his son, the gemara refers to mikra, mishna, talmud, etc. and Rashi (d”h torah) writes that mikra means torah to the exclusion of nevi’im and ketuvim. Apparently the obligation to study mishna takes precedence over the obligation to study nac”h.