Facebook Container makes it harder for Facebook to track you by separating all Facebook content in a separate container to the rest of the web.
DuckDuckGo Privacy Essentials helps prevent most 3rd party trackers. (DuckDuckGo is also a very good search engine and has a couple useful beta features such as a mobile app tracker-blocker and email forwarding service that removes trackers.)
Decentraleyes also helps prevent a lot of third party trackers.
AdBlocker Ultimate is just another standard ad/tracker/popup/etc blocker, which UBlock Origin mostly covers; however, it's managed to block some things for me that UBlock hasn't (i.e. in-site etsy ads, Twitch ads, etc)
The Wayback Machine is the quickest way to archive sites just in case anything happens to them. Try to do this often!
Dark Reader - for dark mode. (this site honestly looks better with it off though lol)
Mobile Dyslexic replaces all fonts with a special dyslexia-friendly font. You could do this through Firefox default font settings if you had another font you wanted.
Redirector redirects sites to other sites. Examples are redirecting to non-fandom.wiki alternatives (see here) or to alternative Twitter viewers like notabird.site.