Most Underrated AdWords' Features in Your Opinion?

After using AdWords for some years, I feel like I have used some features much more than others, such as Keyword Bids, ad copy, landing page, etc. However, I've recently spent a few day to explore Adwords and play with features I didn't or rarely used. And I found some of them to be very useful: Targeting audience by airport and income, and auction insights. Here are some articles explain those examples very well: https://blog.kissmetrics.com/brilliant-adwords-features/ https://supermetrics.com/blog/6-hidden-features-adwords/ It's such a shame that I had no idea about them for a while. What are the useful features but people are not using that much in your opinion?