[Eva]

Combine a natural gas furnace with a heat pump, unless you live somewhere where the temps get below 30 degrees and stay there for long periods of time.

What I can tell you from experience is not scrimp on size. If the furnace is too small for the job, it will run all the time and cost you more to operate. You could lose the savings on the smaller heater in one month.

[virgil283]

"Combine a natural gas furnace with a heat pump"....Ditto, [it is called a piggyback here] this is the best return for the extra 1K it will add to the cost, maybe full recovery in 3 years, Also consider Bryant equipment.