When I worked with a ecommerce site, we had to measure our "enemies", but we didn't had access to their GA information obviously, so how could we know if they had more visits than our site?... and here comes Alexa Top Sites. Maybe the information was not 100% accurate, but we compared the Alexa information with our analytics information, and it was like 80-85%~ near the real one, so we though that we could use that 80% to know the real information about others, and then, use it to know where we can do it better.

1- Helpful in providing the lists of top sites basis the Alexa traffic rank algorithm which helps our developers to better incorporate traffic data into their applications. 2- It's very easy to see global as well as country rank for a website. This helps check the popularity of the website and these days popularity means more money. 3- Lots of details and statistical data is provided.

I like it when ALEXA gave us alot of detailings about statistics and sites. It is very helpful and easy to use, it doesn't have any confusions while using it. Most specially it is free although it have paid options with payment.