It depends on what your needs are....
MCT are used more for therapeutic purposes for those with digestive issues or those who need that specific type of fatty acid. It is also used by athletes b/c it's easier to digest and has been shown to help fuel their exercise. MCT can be found in cold pressed coconut oil.
Avocado oil is rich in mono-unsaturated fatty acids and is also good for cooking due to its high smoke point. It's used more in cooking.
They both have the same amount of calories and fat per serving.