According to WebHVAC, Lennox makes the top-rated heat pumps as of 2015. This site also lists Carrier and Maytag brands as the second and third best heat pump brands based upon efficiency ratings.
Lennox heat pumps provide a reliable source of heat with a fairly high HSPF level, which stands for Heating Seasonal Performance Factor. Higher HSPF ratings indicate less energy is used to produce heat. The Lennox Signature Collection XP25 Heat Pump has a HSPF of 10.2, and features solar modules that produce energy to run the system.
Carrier also offers an efficient heat pump with the Infinity 20 25NVAO Greenspeed model, which has a 13 HSPF rating. Maytag's popular PSH4BI iQ Drive Heat Pump has a 10 HSPF rating.