It partially depends on your climate. I’m in Portland, Maine, so for us, we have a natural gas furnace with radiators, but they’re heavily supplemented by a few heat pumps. For us, the temperature frequently gets very low in the winter, sub 10°F, and this is the point when heat pumps aren’t as efficient. An ideal set up in a small home could be heat pumps running off solar and a woodstove for when it gets really really cold.