Forum:Poll: Most difficult super boss

What "Super Boss" throughout the Kingdom Hearts Series do you think is the most difficult to defeat? Vanitas Remnant (Birth by Sleep) Unknown (Birth by Sleep) Armor of the Master (Birth by Sleep) No Heart (Birth by Sleep) Ice Titan (Kingdom Hearts 1) Phantom (Kingdom Hearts 1) Kurt Ziza (Kingdom Hearts 1) Sephiroth (Kingdom Hearts 1) Xemnas (Kingdom Hearts 1) Dustflier (358/2 Days) Sephiroth (Kingdom Hearts 2) Organization XIII Data Battles (Kingdom Hearts 2) Lingering Will (Kingdom Hearts 2)