I wondered what was the best, in one hand for the health (but I guess the question should be asked somewhere else, shouldn't it?) and in the other hand for the earth.
Which one, if there is one, is more (or less) eco-friendly? Which one is more efficient (space used versus productivity)? Also, depending on our location, consuming one type of oil rather than the other might be worth to consider (depending on where they can grow, where they are usually grown and so the fuel needed to deliver them to our location in one form or another). How many energy is required to process each? Is there more useful byproducts coming from sunflowers or from an olive tree? Etc.
EDIT: Just putting that here: https://duckduckgo.com/?q=sunflower+oil+versus+olive+oil&t=canonical
EDIT: Also, please never forget to check if the oil you are using can be used for cooking or not. Some are very unhealthy to cook. For instance, my sunflower oil says that it shouldn't be cooked over 175 C°. Always check!