Praise be to Allah.
The Sunnah of the Prophet (peace and blessings of Allaah be upon him) was to do a lot of different kinds of worship during Ramadaan. Jibreel used to review the Qur’aan with him at night, and when Jibreel met with him, he was more generous in charity than the blowing wind. He was the most generous of people, and he was at his most generous in Ramadaan. At this time he used to give more in charity and treat people even more kindly; he would read more Qur’aan, pray more, recite more dhikr, and spend time in I’tikaaf (retreat). This is the guidance of the Prophet (peace and blessings of Allaah be upon him) in this aspect of this holy month.
As to whether it is better to read Qur’aan or to pray voluntary prayers, this depends on people’s circumstances, and the true evaluation of this is up to Allaah, because He knows all things.
(From al-Jawaab al-Saheeh min Ahkaam Salaat al-Layl wa’l-Taraaweeh, by Shaykh ‘Abd al-‘Azeez ibn Baaz, p. 45).
A specific action may be better in the case of any given individual, and another may be better for another individual, according to the degree to which a particular action brings a person closer to Allaah. Some people may be influenced more by naafil prayers and may focus on them and do them properly, which will bring them closer to Allaah than other deeds might, so in their case those deeds are better. And Allaah knows best.