The best oil to cook potatoes in is canola oil, vegetable oil or avocado oil which are high smoke point oils.
High smoke point oils are best for cooking potatoes in, as the high smoke point oils also allow for crispy results, while also not affecting the taste of the cooked potatoes.
If you want a richer flavor to your cooked potatoes, you can use lard, bacon grease or even duck fat or goose fat.
Other great options for cooking potatoes are ghee or even a mix of butter and a high smoke point oil, which can help to prevent burning while also still getting some butter flavor.
I prefer using canola oil myself when cooking potatoes.
Peanut oil is also another great cooking oil for cooking potatoes in.
Some restaurants also use peanut oil for cooking their potatoes fries in.
For example five guys uses 100 percent refined peanut oil for cooking their fries and also publicly states it as part of their brand.
And Chick-fil-A, uses peanut oil for their fries and fried chicken, but the use of the peanut oil can pose risks for people with peanut allergies.
Jimmy John's uses peanut oil for their "Jimmy Chips".
Outback Steakhouse uses peanut oil for all of their fried foods.
McDonald's uses a peanut free oil blend for their fries and In-N-Out does not use peanut oil.
Chipotle also does not use peanut oil, although cross contamination is still possible.