I haven't used Linux long yet, I'm more used to Windows. But a big advantage of Linux is offcourse the security and that you know more about what's happening on your computer. It's a big change from Windows to Linux and it's not really advised if you don't know something about computers.
The open-source is also a good advantage as more people workl o it all over the world and Linux is also being updated more often than Windows.
If I buy a computer there's no software installed as I don't like that and because I set the computer together myself. So afterwards I install a OS. Linux is also a lot cheaper (you can get it free or for a small price with a manual) than Windows.
Saying what's the best OS is not easy as each one of them has his advantages and disadvantages. If you choose Linux you have to wonder which distribution you're gonna get.
But there are on this board people who know more about Linux like Choli, PlusFan and others
.