Basically there are four main classifications of furnaces: propane, natural gas, oil, and electric. Some are more economical than others, while others are lower cost. There are pros and cons to all these factors for your home.
The most important thing when it comes to your HVAC system is that it is properly sized for your home. If it isn’t properly sized it will run inefficiently, cost you more money, and not be able to properly control humidity in your home.
As time goes on and your system is operating on a dirty filter, it can cause early system failure. This can be due to your system straining to circulate air and break. This issue is further aggravated if you do not get regular maintenance performed on your system.