You may also want to consider dual fuel/hybrid systems--heat pumps with gas heat backup (as one setup of a dual fuel system). Trane is good as is Carrier (especially the Infinity line of products). The important thing is the installing contractor. I'm in Maryland and it doesn't get quite that cold, but my heat pump keeps up fairly well.

What is your primary source of heat?

What are your electric costs?

A heat pump will work very well to about 32 degrees F outside (give or take a few degrees), provided that it is properly sized, installed, and the ductwork is sufficient. You would need supplimental heating (a gas furnace, etc.) in addition to the heat pump.

Note that heat pumps have a reduced life expectancy (10 - 15 years) compared to straight a/c because they run during all seasons. Also, heat pumps do not put out the 120 degree air temps like furnaces. The temps the heat pump puts out drops with the outdoor temps. Heat pumps typically put out 101 degree air at 50F outside, 97F at 40, 93F at 30, 90 at 20. This is info is not to discourage the choice of a heat pump, but so you are aware of it.

Brand name is not necessarily more important than a quality installation.

If you go with a heat pump, make sure it's a full btu system. Anotherwords, a "4 ton" system gets a full 48,000 btu's, not 45,000. Some mfrs systems are weak on btus. For lower operating costs, get an HSPF of at least 9.

One final note, there is a cold climate, all-electric heat pump called Acadia made by Hallowell. It runs down to the -20F outdoor temps that you have. The technology is a modified heat pump w/booster compressor and economizer. You can search this site for info on this fairly new system.

Best to you.