And the US Army AH-64 Apache and Russian Ka-52 Alligator are generally considered to be the two best military attack helicopters in the world (with the Russian Mi-28N arguably in a close third).

AH-1Z Viper: M197 20mm cannon, Hellfire missiles, Hydra 70 rockets, and AIM-9 Sidewinder. Ka-52 Alligator: 2A42 30mm cannon, Vikhr-1 missiles, S-8 and S-13 rockets, R-73 missiles.