Energy Star's 2015 list of the best SEER rated heat pumps include the Fujitsu Halcyon RL series, LG's LAU/LAN and LSU/LAN models, the Mitsubishi M unit and the Panasonic Inverter. SEER is the Seasonal Energy Efficiency Ratio and measures the amount of cooling a unit delivers per watt of electricity.
Energy Star also rates by EER and HSPF, which the units listed above were the top overall performers in all three categories. The EER, or Energy Efficiency Ratio, is the cooling capacity of an air conditioner in BTUs at 95 F as measured at the Air Conditioning, Heating and Refrigeration Institute. SEER is considered more realistic because it uses the cooling season with variable temperatures. HSPF is the Heating Seasonal Performance Factor and it is the heating equivalent to SEER for heat pumps.