When considering a heat pump vs furnace it's going to come down to the ambient temperature

A heat pump works by extracting thermal energy from the outside and transferring it inside (which is just the AC cycle in reverse). The benefit of this is that you're not (directly) thermodynamically limited by the energy you're inputting into the system.
Since you're just transferring existing energy from one location to another, we can transfer more energy than we put into the system. [fwiw there are thermodynamic limits involved in all of this but that's a much more complex discussion]

There's a pretty classic thought experiment. What happens to the temperature of a room if you open the refrigerator? Since the heat source and sink are both now connected to the same air, the air heats up due to the energy required to run the compressor and electrical losses. The energy transferred from one side of the cooling loop to another simply equalizes back out.

Since a heat pump works by moving thermal energy against a thermal gradient, its "efficiency" is going to depend on the size of that gradient. The larger the gradient the less viable heat pumps are to use.

In western Washington temperatures are well within the range where heat pumps make sense. In eastern Washington, it's a much more nuanced conversation.