This is upon opinion of a PvPer bunny.
Both of my head/mask are AC,
Though I do have an AP head/mask (I rarely use them)
Since i am sacrificing alot of AP with AC equips, I then got anything with a high AC base
and comped it with AP, not satisfied if it doesn't hit the 1k AP mark
I still gain up to 1k ac and 17k ap which is enough for me.
It depends on the balance you have already I guess.
is best for boss hunting.
is best for PvP
is best for killing sense, magic, power types in PvP.
is best for killing all types in pvp >
As long as you have 12k+
AP you'll be fine :3.
I advise you get yourself a pwf so you don't have to rely on AP equips while sacrifcing your AC. But bear in mind, this is for PvP.
AP/HP all the way for PvM