This question sounds suspiciously like a test interview question. The appropriate answer in this context is a series of questions, like "What are the most important things to test, in your opinion?" "What areas of concern do you have?" "What areas are most important to our customers?"
There are a bazillion different ways and things to test, including usability, connectivity, reliability, portability, expandability, understandability, studiness, security, the list goes on. There is no magic top 10 list other than in the mind of the interviewer. What the interviewer is looking for is *not* a top 10 list. They are looking for your ability to ask intelligent follow-up questions.