Originally Posted by
Morion
An increase in damage from Agi outweights the increase in damage required to produce a shield resulting from the additional AP from Agi, therefore Agi is contributing to the increase in Statue shields. Besides, given that they scale on AP, Agi also increase the amount absorbed. Overall, while crit would be better to increase the frequency of procs, Agi is better than crit to increase the efficiency of the statue when you combine frequency and amount absorbed. But you must remember that you gain twice more crit from a gem, making agi gems and crit gems roughly equal considering the Statue (very roughly, the exact ratio depends on current values of crit, agi, weapon dps and Vengeance).