I find that this question opens the door to further questions and enables someone to highlight themselves in a specific, non-generic way.

Plus additional questions can easily follow: What position did you hold when you achieved this accomplishment? How did it impact your growth at the company? Who else was involved and how did the accomplishment impact your team?

Discussing a single accomplishment is an easy way to open doors to additional information and insight about the person, their work habits, and how they work with others.