First, decide if you have access to either one already via your current appliances at home before shopping around. If so, there are several factors that will determine which fuel source works best for you: environmental impact being one since methane emissions are higher than propane and coal and oil, so if you’re concerned about the environment, that’s a big one to consider.
One consideration is whether or not your home has gas lines already installed which would allow for easy access since an appliance using natural gas can be turned on with just a flip of switch whereas propane requires more work such as hooking it up yourself to fill up tanks outside whenever needed or paying someone else to do it.
Finally, there are cost considerations involved when choosing between options because while both types of fuel sources will get their own type of fireplace burning at upwards of 90-100 million BTU’s per hour (which is extremely hot!), they also carry different costs depending upon where you live in terms of availability and convenience along with how much usage you have in a year.
Think about all of these things before making your final decision and then decide which one is best for you!