Heating, hands down in that scenario. You would almost certainly have the heat strips on, assuming the system uses that type of auxiliary heat.

Even without using heat strips, you require (in general) more btus for heat. Look at the delta Ts (difference in temp between indoor and outdoor) and see what I mean. Now - real world doesn't work exactly that way because windows bring in heat from the sun and people generate heat and electronics generate heat. But you are comparing a 20 degree delta T to a 50 degree delta T. The insensible heat gains might be worth 10-15 degrees so heating will still use more BTUs.

hvac 20 yrs old,ac leaking badly.even pay elect $113 and nat gas $71 per month(include household power well,gas water htr),looking at new system 15 seer and 96%variable speed furnacefor about$12K. someone sad check ground water heat pump, est:$18k how much m,ore efficient is ht pump for payback live in western iowa. which do i get

It'll certainly, on average, cost more to heat than cool. A lot of areas now impose summer electrical rates which are higher than winter rates so they may be close. As for determining the cost effectiveness in relation to higher initial costs of higher SEER ratings, there may be more sizzle than steak. Compare the increase in energy savings with the higher efficiency units as opposed to the actual higher cost of a higher efficiency unit. The expected life cycle on a unit is 10 years so figure the energy savings you will experience in your area and see if it will shadow the initial and ongoing maintenance costs. Keep in mind the newer units also have a maintenance schedule that will be required by most companies, which is going to increase those costs. If your energy savings is more than the overall cost of the unit in a 10 year period, then it's worth it. But for the most part, I think you'll find it won't.