If you are looking for an operating system that offers the best values, none can compare to Linux.
First of all, it's free. Most Linux distributions can be downloaded gratis from the developers' Web site and you can install it on however many computers you want. Secondly, it comes with a lot of things, such as office tools (word processing, spreadsheet, presentation), audio and video playback, Internet and e-mail, instant messaging, and so on. Basically everything a general user would want to use with a computer is there when the installation is done. For those applications that are not there, chances are you can download them for free.