The best automated deployment tool is... the one that fits your needs
The process of getting a completed feature or bug fix code from the development environment to your web servers is web software deployment. We have been deploying code in various ways, a decade back we were used to uploading our files using File Transfer Protocol (FTP). I would not considering copying files from the development machine to a web server a form of automated deployment, basically it was a necessary evil at that time.
If you still use FTP at this time like 22% of Nepali developers you really need to move on. In this post I will briefly mention some deployment tools and try to analyze their pros and cons. Still as the title reads the best automated deployment tool is the one that best fits your needs.