What KPI do you think is most important?
This is a broad question. As long as you give an answer that demonstrates you have a solid understanding of KPIs (key performance indicators), the interviewer will most likely be satisfied.
It's best to give an answer that emphasizes your experience using KPIs to measure your success. If possible, answer with a specific example. Otherwise, make sure your answer reflects your understanding of a variety of KPIs.
"Revenue is obviously one of the most effective KPIs, but I think that measuring product usage gives a lot of insight and should be considered an important KPI. This is especially true in terms of measuring specific feature usage, as the data can feed back into product development as well as influence future marketing campaigns."
