Is Overhaste or Double Attack better for killing?

[Druegar]

's effect "Taelosian Guard" gives 8% Overhaste (v3) and 8 HP regen

's effect "Stoic Wolf Familiar" increases Double Attack by 6% and has 6 HP regen

I have worn (regular) haste of 45% and access to both enchanter and shaman haste buffs. My primary role is tanking/DPSing undead in a 3/4 boxing situation, so my goal is to kill as quickly as possible. I'm not sure if the additional haste or double attack would be the superior choice.

Thank you for your opinions/advice.

[Zyba]

[Ughbash]

[knytul]

[Khael]

[kolor]

overhaste by far
ferocity/aas/buffs for double attack

[Kruzar]

[Druegar]