There are two types of oil - the oil to put on the griddle and the oil to mix in the pancake mix. We are talking about the pancake mix here. It's not possible to single out a particular oil because preferences and recipes vary.
One of the best options is canola oil. Inexpensive and does not change the flavor of the pancake base.
Coconut oil is another oil that you can use in making pancakes. Depending on your taste preference, look for flavored or unflavored coconut oil.
Grapeseed is the other type of oil that I would recommend. It's clean and light, which makes it great for making pancakes.