well i feel ac is not a factor, as you dont have a choice, not like you can get ac aug 5, as far as i know, so you are stuckj with whatever they give ya on items that do have ac.
War: AC -> H.Agi -> H.Sta -> H.Str (if tanking with shield)/H.Dex(if Dual wielding)
this is my personal experience, running a tank through all of eok progression with a zerker and shaman support.
and yes i dual wield on him most fights, cause its so good dps wise, but you lose mitigation, is why dex can help with evasion and more dex is more connecting hits or some such, i forget.
now for paladins and sks, since they dont dual wield, but some of their damage and defensive stuff comes from procs, maybe balanced dex and str as they often are shield bound wiht massive damage dealing 1handers.
again all this is from personal experience playing all 3 classes.