What is the most valuable personality trait to have?
The answer, according to research, is CONSCIENTIOUSNESS.
"It turns out that conscientiousness is the only major personality trait that leads to success and is the most most valuable personality trait."
Conscientious is defined as: (of a person) wishing to do what is right, especially to do one's work or duty well and thoroughly.
Psychology today says:
Conscientiousness is a fundamental personality trait—one of the Big Five—that reflects the tendency to be responsible, organized, hard-working, goal-directed, and to adhere to norms and rules. Like the other core personality factors, it has multiple facets; conscientiousness comprises self-control, industriousness, responsibility, and reliability.