The real answer is how much money do you want to spend on an on-going basis? We now have fluid charged systems that are nearly 100% efficient. They can be extremely expensive to install, however.

Most of us like an air blowing system for moving stagnant air around, along with quick rises in temperature, or lowering, as the case might be. Moving air around in a super tight home is very desirable, coupled with an energy recovery exchanger, to bring outside air into the home.

Zoning is one characteristic I love. I like areas of my home to be cooler (bedrooms) and other areas warmer (baths). We have to be careful with zoning of heat pump systems; if we throttle back too much, we can burn the pump up. As I grow older in the NW, I really like radiant floor heat, throughout the home, especially with its zoning capacity.