I vote rotors for distribution efficiency. A well designed rotor (which includes about all made today) will spray close in to themselves too - Toro MultiStream and MP Rotators are good examples. You can also add the advantage of rotor's quiet operation and low precip-rates for little to no runoff as bonuses. In my very humble opinion, impacts were state of the art decades ago - before such things as water rationing and efficiency were even heard of. All the lab tests prove without a doubt that rotors can achieve the highest distribution efficiency you can buy - short of flood / basin irrigation.
