Which oil is best for cooking?

Depending on the food.

My general rule is to use the oil that is traditionally used in the dish or recipe. Ancient food knowledge includes ecology, economy, and, most importantly, taste, which is correlated with the type of oil used in a recipe or dish.

For instance, I find that coconut oil does not work well for spaghetti alio olio. It wouldn't even taste good. Italian nonnas use the appropriate amount of olive oil because the Mediterranean region has an abundance of olive trees, which keeps the oil quite fresh and helps the local farmer. As we all know, a significant part of the neighbourhood economy is agriculture. I must therefore use high-quality olive oil to obtain the genuine flavour and experience by relying on ancient food knowledge that has been passed down by Italians who understood that using olive oil when cooking would be delicious and healthy.

Similar to this, in order to achieve the desired flavour when preparing a Bengali dish, I must use excellent mustard oil (ideally, the same brand as the locals).

For my traditional recipes, I use high-quality filtered (as opposed to refined) groundnut oil in my daily cooking. The same dishes that I now make were made with it by my grandmother and her mother, and it is delicious and healthy.

When the right conditions and season exist, local farmers in Maharashtra and India produce large quantities of groundnut oil, so I can be sure that the oil hasn't travelled very many "food miles" to get to me. Consequently, I'm here supporting my neighbourhood farmer by consuming groundnut oil the ecology as well as the regional economy. Win-win for all!

I think you get my drift. Hope this helps!