What are the most important features to consider when purchasing an Audi A5?

I'm looking to buy an Audi A5 and I want to make sure I consider all the important features before making my decision. What should I prioritize and how do they compare between different models?

It's essential to consider the engine type and size, as this will affect both performance and fuel efficiency. Additionally, take into account the technology and safety features available, such as blind spot monitoring and adaptive cruise control.