The best popcorn oil can differ from one situation to another, and in order to make the right choice you will need to take your own tastes and health concerns into account. Good popcorn oil needs to be able to stand up to high temperatures, and not impart any undesired flavors to the finished product. Many people prefer coconut oil for this purpose, since it stands up to heat well and offers a good flavor. If you are concerned about your saturated fat intake though, you might want to choose an oil like canola. It is also possible to make popcorn without oil, in an air popper or microwave, if you need to avoid all types of fats.
Popcorn oil is an ingredient that is needed in order to make popcorn in kettles and many conventional popcorn makers. The oil is heated to a temperature great enough to excite the water molecules inside each popcorn kernel, causing them to pop open. Since the oil is heated to such great temperatures, some oils are not suited to this purpose. Substances with low smoke points, such as vegetable oil, should not be used to make popcorn. Any other oil that can withstand the necessary heat can be used to make popcorn, though some taste better, and some are better for people with certain dietary restrictions.
Choosing the best popcorn oil can be difficult, since there are so many options. Each different type of oil can impart its own unique flavor characteristics to the popcorn, so you might want to take that into consideration. Coconut oil is typically considered to provide the best flavor, and many movie theaters, and similar venues, use it to make their popcorn. There are also specialty oil mixtures that are formulated specifically for use with popcorn, and in many cases you will not need to add butter or salt when using them. You might need to try several different types of oil in order to find out which one tastes the best to you.
There are also health concerns that can come into play when selecting popcorn oil, especially if you need to watch your saturated or trans fat intake. Coconut oil contains saturated fat, so you might want to look at an alternative if you are concerned about that. Some specialty popcorn oils also contain saturated or trans fats, so it is important to read the nutritional information when choosing oil. Canola is one option that is lower in saturated fat, yet capable of withstanding the heat in a kettle.