For slightly lower heat I use coconut oil or if I want a little sweeter flavor - say for grilling onions for instance.

I use olive oil at below medium to cook salmon mainly. Sometimes avocado oil for that as well as it has a very light flavor.

 

It's not just the oil you use but how high the heat is when using it. When you cook it at too high a heat the oil degraded which for one tastes bad and two is bad for you as it’s been destroyed by the heat and lost molecular cohesion changing to a less healthy form of fat. Unsaturated fats do this much easier because molecularly they are far less sturdy and stable than saturated fats are.

 

Olive oil is a monounsaturated fat and research shows that monounsaturated fats help keep “bad” LDL cholesterol low and boost levels of “good” HDL cholesterol. In addition, extra-virgin olive oil is high in antioxidants called polyphenols that have been linked to heart health. “Pure” olive oil (i.e., not virgin)doesn’t contain these “bonus” antioxidants. Use olive oil in dishes that benefit from its rich flavor. Drizzle it on steamed vegetables, mix it into a salad dressing, and use a little to sauté vegetables. Or use it in baking in place of butter. buy canola oil is Neutral flavor and a high smoke point—the point at which an oil begins to smoke—make canola an excellent choice for baking and sautéing. Smoke point is an important consideration if you’re planning to cook at high heat—as you do when you’re frying or grilling. At an oil’s smoke point, nutrients are destroyed and potentially health-harming compounds are formed. Canola oil generally doesn’t have many antioxidants, as olive oil does, but it does have a relatively long shelf life. In addition, canola is the richest cooking-oil source of alpha-linolenic acid, an omega-3 fat that has been linked to heart health.

 

Olive oil is the best with so many proven health benefits. It has a low temperature before smoking. For deep frying, Canola is the best. It reaches 375 degrees without smoking. Perfect temperature for deep frying chicken fries etcetera. It too is rich in omega 3s. Corn isn't good for you. Vegetable oil's issue I & many cooks have is what kind of vegetables is it made of. Many brands are worse than butter. Crisco is 10 times higher in saturated fat than butter. Butter in moderation is good for cooking too not deep frying though more for sauntering & for baking.