I have a number of computers each with one or two Operating Systems installed. In my line of work, the more operating systems I know, the more clients I can help which turns into more money for me. My main business laptop computer has Windows 10 on it and I carry another one with me that has Linux Mint 17.2 and Windows 7 in a dual-boot setup. Additionally, I have older computers with older operating systems on them: Windows XP, Windows 2000, Windows 98, Linux Ubuntu 12, and Windows 8. I keep these in case I need to brush up on an Operating system I will be seeing at a client. I also have an Apple laptop and desktop so I can stay current with Apple computers. Of all the operating systems I use, my favorite is Linux Mint 17. Second place is Microsoft Windows 10 partly because of the administrative tools and also because it is pretty fast. I have it running on an old Dell laptop which originally shipped with Windows XP in 2007 and I’m amazed how fast it is! In the future I want to setup a laptop to dual-boot Windows 10 and Linux Mint. I like Linux Mint because of it’s robustness, speed and security. I don’t worry about viruses when using Linux as I do with Windows. There are so many free, good programs available from the software manager in Linux and you don’t have to go to the internet to download them like I do in Microsoft Windows. My favorite older operating systems are Windows 2000 pro and Ubuntu Linux 10.X What is your favorite?