The phrase "most bull-headed" refers to an individual who is stubborn, obstinate, or adamant. The opposite of this personality trait would be someone who is flexible, adaptable, or open-minded. These antonyms suggest a willingness to consider other perspectives and ideas, and to change one's opinion if necessary. A person with these qualities may be described as easy-going, open-minded, or flexible. While bull-headedness can be helpful in some situations, such as when standing up for one's beliefs, it can also be detrimental in others, such as when refusing to listen to feedback or advice. Therefore, embracing more flexible and open-minded traits may lead to greater success and happiness in life.