There is no single personal strength that works best in every job interview situation. Certain qualities, such as excellent communication skills, organizational skills and thoroughness, commonly apply. However, the best response to a "strengths" question is to emphasize a few of your best personal strengths that align with the most critical skills needed for the job. You can look over the job description and list your skills to work out your answer ahead of time.
Many job descriptions indicate a need for some level of communication skills. After all, few jobs don't involve any type of interpersonal or group communication. This skill set is especially useful in jobs dealing with customers, the public or groups. If answering about personal strengths in a sales interview, you might say "I have excellent communication skills, which I applied successfully in my previous sales job to exceed my quota every month and to achieve high customer satisfaction reports."
Organizational skills are another fairly common skill set required in many jobs. In particular, careers that involve office management, maintenance of customer or supplier files and multiple daily activities require excellent organization. In answering the strengths question for this type of position, you might say "I have developed a strong reputation for having excellent organizational skills in my office management career. I have routinely received superior ratings on evaluations in this skill." Of course, this example is only sincere and honest if you have the skills and your example is truthful.
Many employers or careers also place high demand on an employee's versatility or flexibility. This point is most true in jobs that involve multitasking or where employees play varying roles throughout a typical day or week. Hospitality career website HCareers points out that flexibility is routinely need in food service. Thus, you might say "I have worked as a head chef in some of the most fast-paced restaurants in New York. This experience has allowed me to become extremely flexible in moving from preparing food to leading employees and performing administrative tasks of the job."
If you apply for a job where you come up with original ideas, products or processes, creativity is likely a key skill desired by the hiring manager. Naturally, you should have the skill to get the job, but also to enjoy your work. If so, you might say "Creativity is one of my greatest strengths. I came up with a new service process in my last job that helped increase our first-call success rate by 7 percent within three months."