The choices of home heating furnaces can be bewildering - sometimes you might feel like giving up and asking a salesman for anything that will meet your needs. This could be a mistake though, since there are so many choices that the salesman will have to take an educated guess on your behalf. But you know your own circumstances better than anyone, so invest a little time learning about the options.
A good time to start looking at your home heating options is when you do not need to - if you wait until the current furnace is failing then you will be rushed into a decision. You know if it is old and maybe living on borrowed time, so start researching.
Start by thinking about fuel. Electricity has some advantages since it does not need special hook up or fuel deliveries. It has improved a lot over recent years, and your home heating needs may be met by the best rated heat pumps.
Oil fired home boilers remain a popular choice for bigger furnace applications - of course the fuel will need to be delivered, but the tanks tend to big and last a long time.
Gas home heating boilers get the thumbs up from lots of people, particularly those in natural gas supply areas. They are clean and do not need much maintenance.
If you have time on your side, you could investigate some of the slightly more unusual options - home wood fired boilers or home corn heating furnaces for example...