What you want is a high iodine value. Both avocado and olive oil have low iodine values, and they’re premium oils, so doubly wasteful for cast iron seasoning.
I think the idea is the higher the smoke point the easier it is to bring the oil to a high temperature to get it to polymerize. I don't know if this is true, as my pan came preseasoned and then I mainly add to that by carbonizing previous bits.
What you want is a high iodine value. Both avocado and olive oil have low iodine values, and they’re premium oils, so doubly wasteful for cast iron seasoning.