Antonyms for the word "most out-of-sorts" would be "calm," "composed," "content," "at ease," "peaceful," and "serene." These antonyms describe an individual who is emotionally stable, well-adjusted, and in control of their emotions. Such a person is not easily upset or agitated, and tends to have a positive outlook on life. They are comfortable with themselves and their surroundings and are able to maintain a sense of balance and tranquility even in stressful situations. Unlike someone who is "most out-of-sorts," these individuals are able to approach challenges and difficulties with a clear mind and a positive attitude.