when are stats more important than att?

Well, for physical attackers, it really does depend. Wep. attack adds more damage, but STR adds HP, DEX adds avoidability and accuracy, and LUK adds... hands. Although if you're going ___-less, Wep. Attack>Stats all the time, as you're going for damage anyway.

If you're a magician, 1 INT=1 Magic Attack, however INT adds magic defense as well. Therefore, INT>Magic Attack.