Weapon damage is just about always the best stat. 1 wd is worth about 7-9 INT.

If I understand correctly you are saying
iLevel 55: WD 59, INT 15
iLevel 70: WD 57, INT 17

Strangely the ilevel 55 item, if I understand your description as the stats above, is the better choice. I'm guessing it's HQ while the i70 is not.