Electricity has been the most costly in the past 30 years, but with energy costs jump on oil it may be the way to heat and cool the home.
Next to electricity gas would be the easiest product to maintain.
Simple concepts and the largest number of contractors work with this type of equipment.
Gas has long been the leader in affordable heat.
Oil is a good option, the concepts are simple but there are very few contractors who really understand how to fix the equipment when it needs maintenance.
Some solar systems are very easy with little to no maintenance.
However, the investment and size of the equipment is often large for the small return of investment.
Wood, appears to be cheep, but requires vehicles, chain saws, a huge source of wood and teenagers.
Dual fuel, Water source heat pumps, and much more are good options.
The concepts are simple but there are very few contractors who really understand how to fix the equipment when it needs maintenance.