Debian is a preferred Linux distribution, that's used mainly on desktop computers, but many people have started using it lately as a web server OS too, because of the stability and security it supplies. The latter is a consequence of the fact that Debian is developed and supported by numerous qualified volunteers worldwide, which means that any patch that is required to fix a certain issue is released in a couple of days. The same community can also help with any question or problem which a user may ever have, since they can be contacted through email using mailing lists and a qualified response will be sent in around 15-20 min. The advantage here is that all of your questions will be replied by the same people who have designed the Operating System itself and they have a detailed knowledge of how it works. As Debian is free, you won't have to pay any license fees to use it and you can personalize it as much as you want or need. This is valid for both the Operating System as well as the 30.000+ software packages that are available for it.