Might be in the minority here but personally I think the Best helicopter LEGO ever made was the Dino Attack T-1 Typhoon. What do you consider the best one they made? :
LEGO 7477 T-1 Typhoon vs. T-Rex Instructions, Dino Attack
LEGO 5886 T-Rex Hunter Set Parts Inventory and Instructions - LEGO Reference Guide
LEGO 7477 T-1 Typhoon vs. T-Rex Instructions, Dino Attack
LEGO 7477 T1 Typhoon vs. T-Rex Set Parts Inventory and Instructions - LEGO Reference Guide
LEGO 7298 Dino Air tracker Instructions, Dino 2010