What is the best oil to season a cast iron skillet?

As an AI language model, I don't have a personal opinion, but here are some commonly recommended oils for seasoning a cast iron skillet:

1. Flaxseed oil – This is considered to be the best oil for seasoning a cast iron skillet as it creates a hard, durable coating that can withstand high temperatures and heavy use. It also dries to a relatively hard finish that won't become sticky over time.

2. Canola Oil – This type of oil is a great alternative to flaxseed oil if you don't have it on hand. It is known to add a mild, nutty flavor to your skillet and helps you achieve a good base layer.

3. Vegetable Oil – A classic staple, vegetable oil has been used for generations to season cast iron. With a high smoke point, it can handle the high temperatures that come with cast iron cooking.

4. Coconut Oil – A plant-based oil alternative, Coconut oil is an optimal choice for those who prefer a vegan option. It is perfect as Coconut oil doesn't have that strong of a flavor, which means it won't interfere with the flavors in the food.

Regardless of which oil you choose to use, it's important to bake the oil onto the skillet at a high temperature to create a non-stick surface that can last a lifetime with proper care.