From the viewpoint of security, which operating system is best? Let’s consider Windows.
How should we think of Windows? Think of Windows as an open window upon your private information. Think of an operating system as a bank, and think of the hard drive as a safe.
So thinking of Windows as a bank: it has a front door, a side door, a revolving door, trap doors, hidden doors in the basement, in the sides of the building, and in the roof. It has back doors. It’s Swiss Cheese.
Windows is to be avoided. Windows plays dirty tricks to collect information on you. In fact, any operating system from a big company in the United States is to be avoided because of the amount of collection and analysis which will be done upon you. Even worse, Windows is the most frequently attacked operating system in the world. If you use Windows, then you are passively giving yourself over to collection from a big company; even worse, you are risking the exposure of your private information to criminals because the kernel of Windows has a huge attack surface.
Operating systems from big US companies are designed to collect on you, and hackers of all stripes, to include hardened professional criminals, piggy-back on the industry’s modes of collection. It is difficult to determine whether or not big US companies are in cahoots with national-level US intelligence agencies, in order to knock holes in popular products.
So, for the general user who wants to emphasize security, which operating system is the best choice?
Linux-based operating systems are inherently more secure because the kernel is configured more safely, and most malware is written for Windows. It is very important to emphasize that no operating system is going to grant you absolute security. They are all attacked in similar ways. That said, you can still do a lot to protect yourself.
The safest OS out there is clearly TAILS. Patriot COMSEC also recommends Fedora. TAILS focuses on security, and Fedora does a good job with its security updates. Both TAILS and Fedora are easy to use. TAILS comes with cryptographic and security tools, such as the one that erases meta-content. A lot of people like Open-BSD, Puppy, or Ubuntu. Ubuntu is a doubtful case because one can tell that it does not care much about security; for example, if you try to generate PGP keys on Ubuntu, you will find that they have been weakened. They are not made to be secure by default. ClamAV is another suspicious operation. At Patriot COMSEC we don’t like Ubuntu. Puppy is recommended for the general user, and it has the further benefit of being able to run only in memory.
For a hand-held device, whether it is from Apple or if it is Android, there is no good alternative. Apple devices are wonderful at being controlled remotely, and Android apps come from here, there, and everywhere, resulting in a security nightmare. If you are a diplomat, a negotiator, a whistle-blower, a Wall Street lawyer, someone with a security clearance from your country and you are overseas, you need to turn your mobile device off and put it in a metal container that does not emit RF or allow in sound. Those devices are not safe, period.
For the general user, and for the advanced user who wants a system that touches the internet, TAILS is the best choice. TAILS can also grant anonymity. Fedora, Qubes, Open BSD, and Puppy, are preferable to what is made by a big collector such as Google, Microsoft, or Apple.
Lastly, one could get on the internet and find flavors of Linux made by small companies in Europe and elsewhere.