If you don't have natural gas or want to burn wood, basically your only choice is electric resistive heating (COP = 1) or an air source heat pump (COP > 1, abov

If you don't have natural gas or want to burn wood, basically your only choice is electric resistive heating (COP = 1) or an air source heat pump (COP > 1, above 10-15F) (other options like ground/water source heat pumps are possible but expensive/need specific conditions), the heat pump option will be more efficient, even in a cold place. When it gets cold enough that the heat pump isn't performing you simply turn on the auxiliary resistive heaters instead, there will at least be some days in the shoulder season where the heatpump is beneficial from an efficiency standpoint. If it makes economic sense is another matter. I think if you are going to get central AC or a minisplit its not that much more expensive to get a heatpump. If you have natural gas it makes sense, economically, to use that to heat most places in the USA.