Best general-purpose Operating System
QubesOS is still (and has been for some years) the most secure general-purpose operating system for computer users who wish to protect their privacy and maintain control over their computers and data. It’s great to see the Qubes OS project to gain a lot of mainstream traction and recognition.
I recommend Qubes OS for any power user who can handle the added administration/knowledge required.
Best Operating System to use in hostile situations
TAILS is still the best operating system for use in hostile situations – when one needs to keep what they’re doing on a computer as discreet as possible.
Best way of communicating securely/privately with others
For day-to-day secure communication I recommend the Signal app on an Android phone or iPhone, or on your personal computer. It’s the only app via which I will share photos/videos of my kids with friends and family, or indeed the only app via which I will discuss anything with anyone.
Email is not dead yet, but given how horrible its privacy features are, its use should be reduced to just the few cases for which an instant messaging application like Signal is not convenient.