The answer, as with many things, is "it depends." All other things being equal, air conditioning is a little cooler on a degree-by-degree basis than some forms

The answer, as with many things, is "it depends." All other things being equal, air conditioning is a little cooler on a degree-by-degree basis than some forms of heating...but it never is that simple. Heat pumps have a higher cost to entry but lower operating costs, air conditioners have a lower cost of entry but nontrivially higher operating costs. A common pattern is to use heat pumps, ducted or no, for high-efficiency cooling and heating, with a backup solution like a gas furnace for heating below the point where a heat pump can function.