This was similar to my reaction to that question, and how I'd respond to it in the interview (with curiosity around what they're trying to get out of it). It's not that I don't have strong opinions, but they are necessarily couched in context. Strong opinions lacking in context are a sign of a lack of experience. Sometimes unit tests are a must, and in other cases they are an absolute waste of time. Sometimes microservices are the right call, and others they are an unnecessary complexity. The more experience in this field I get, the more gray and amorphous my opinions become, and "it depends" is the default, if not interesting, answer.