DESKTOP & SERVER OPERATING SYSTEMS

OpenBSD: Arguably the most secure desktop operating system in the world, this is my first choice for desktop systems and servers.
GNU/Linux: While linux has gone downhill over the years in terms of bloat and invasive software such as systemd, this still remains the best option for desktop and server use when OpenBSD can't fill the role.

MOBILE OPERATING SYSTEMS

GrapheneOS: This is essentially a fork of AOSP (Android Open Source Project) before any of the proprietary google spyware crap has been added. This is an extremely hardened version of base android with all apps sandboxed by default, as well as many other security enhancements. GrapheneOS contains absolutely no Google software, services, or trackers, while still offering the same ease of use and software options as the common google android devices available today. If required, google services can be installed at the application level which is sandboxed to prevent any unwanted activity or data mining.

Molly / Signal: Molly is a hardended version of Signal with additional security enhancements. Both Molly and Signal are end to end encrypted messengers that rely on a centralized server and use your personal cell number as your account identifier. Molly offers the option to use Google FCM for push notifications or a fully FOSS version without any google dependencies. This is a great option for people you communicate with who already know your phone number. While it is a centralized service, recent FBI data leaks and subpeonas have proven that they store no metadata of value to anyone.
Session: Session is an end to end encrypted messenger that relies on "Session IDs" as account names rather than any personal identifiable information. The service also has no centralized servers and instead relies on it's own implementation of an onion routing network similar to Tor. This is an excellent option to communicate with people that you don't know since you don't need to reveal your identity and your IP address is hidden due to the onion routing nodes. Unfortunately notifications are extremely slow when google services aren't running. Hopefully this will be fixed in the near future.

Protonmail: Likely the most popular privacy respecting email provider, all emails are encrypted at rest and emails sent between Protonmal accounts are end to end encrypted. The web UI is as good as it gets for web based email providers.
Tutanota: This company and staff seem to be more passionate about privacy and doing things the right way. Emails are encrypted at rest and emails sent between Tutanota accounts are end to end encrypted. While I do love the privacy focus Tutanota offers, the web UI unfortunately just isn't comparable to Protonmail.

Mullvad: Mullvad offers no affiliate program so you likely haven't been spammed with their ads as you have from other providers. Instead, they rely on real recommendations through word of mouth. They offer (and recommend) that you do not give them any personal information when signing up, such as email addresses or credit card info. Account names are randomly generated numbers and they accept payments via bitcoin and monero, ensuring that even they do not know who you are.

Decloudus: From my experience, this is one of the best DNS service providers available. They do not log anything by default and have a very strong commitment to privacy. They include a very thorough ad and tracker block list by default, and offer many filtering options such as the ability to block google and facebook IP addresses. As required by any truly privacy respecting company, they accept payments via bitcoin to protect your identity.

Gadgetbridge: This is an open source mobile app that can be paired with many smart watches to replace the standard proprietary data mining apps that these companies want you to use. As a result, the watch becomes unable to leak your personal information back to the manufacturer. I have this paired with an Amazfit GTR 3 and it works flawlessly. This watch with it's native mobile app would be a privacy nightmare otherwise.