OK this is what you need to do, step one is to figurer out what your degree days are for you area. This is a fact put out by the weather service so you can estimate how many degree days you have to heat for. second is to determine how much energy/ insulation your home has as this will change all the numbers quoted by those experts. i can make the above very greatly. (example my house and my neighborers hose were identical constructed and heated with heat pumps. I super insulated my house and his last month heating bill was 320 dollar . My heating bill was 88 dollars. ) this insulation values critical in energy usage. next BTU is BTU . the only difference is the cost per BTU. Find the one that is the cheapest or bets fits your lifestyle. you can find all this information on a web site called ‘build it solar dot com.” he sells nothing and has every calculator you may need to make a decision..