My favourites:
Augmented Steam - Augmented Steam is a browser extension by IsThereAnyDeal that improves your experience on the Steam platform by providing helpful information and tons of customization options.
Bitwarden Password Manager - At home, at work, or on the go, Bitwarden easily secures all your passwords, passkeys, and sensitive information.
ClearURLs - Removes tracking elements from URLs
Dictionary Anywhere - View definitions easily as you browse the web. Double-click any word to view its definition in a small pop-up bubble. It also supports Spanish, German, French language alongside English. Enjoy Reading Uninterrupted!!!
Don't track me Google - Removes the annoying link-conversion at Google Search / maps / ...
Facebook Container - Prevent Facebook from tracking you around the web. The Facebook Container extension for Firefox helps you take control and isolate your web activity from Facebook.
Google Container - Prevent Google from tracking you around the web. The Google Container extension helps you take control and isolate your web activity from Google.
LibRedirect - Redirects YouTube, Twitter, TikTok... requests to alternative privacy friendly frontends.
Sidebery - Vertical tabs tree and bookmarks in sidebar with advanced containers configuration, grouping and many other features.
Startpage - This search engine extension protects users from being tracked while allowing them to search the web in complete privacy. Startpage is a private search engine with no tracking, storing, or selling users’ search history.
Undo Close Tab - Allows you to restore the tab you just closed with a single click—plus it can offer a list of recently closed tabs within a convenient context menu.
uBlock Origin - Finally, an efficient wide-spectrum content blocker. Easy on CPU and memory.
Today I noticed that I've saved this post for later when somebody adds their favorite extensions but apparently nobody did, so I just wanted to say thanks for this list. I now use most of these.