Given the attack surface of addons, I’ve downsized my addon usage.

• I’ve replaced HTTPS-Everywhere with the built-in HTTPS-first/only modes in FF and Chromium.

• In FF, I use userContent.css instead of Stylus.

• I use uBlock Origin’s url-rewriting filters in place of redirection addons.

• In Chromium, you can choose to have an addon only be enabled on certain sites. I do this with Stylus and Dark Background Light Text.

EDIT: more information:

• I have a shell script that uses regex to “clean” urls in the clipboard and remove tracking params instead of the CleanURLs addon, since this is most useful when sharing links with others. I’ve gotten in the habit of previewing URL content before navigation (e.g. with a mouseover or by pasting into the URL bar) as well. If I want to navigate to a messy url, I just copy it and enter a keybind to clean the copied URL.

I use multiple browsers and profiles.

• Normal browsers: Firefox with Cookie Autodelete, uBO, Stylus, Dark Background and Light Text; Chromium with uBO and Stylus. Stylus is only selective enabled.

• For security-sensitive non-anonymous stuff, I run Chromium with flags to disable JIT and to disable JS by default, in a bubblewrap sandbox. This browser profile has no addons.

• For peak anonymity (e.g. when using one of my anon alts), I run the Tor Browser in a Whonix VM. For quick anonymity I just use the regular Tor Browser Bundle in a bubblewrap sandbox. In an act of mercy towards my weak 2013 Haswell laptop’s battery, I no longer run Qubes. The Tor Browser should not ever be used with custom addons if you want anonymity.

Because the Tor browser should never run with addons and because I use a browser profile that has none, I don’t want addons to be a “crutch” that I depend on too much.

I do global hostname-blocking at the DNS level, so I can live without an adblocker. DNS blocking doesn’t do fine-grained subpage-blocking, conditional blocks, cosmetic filtering, redirects, etc. so a more complete solution is still worthwhile.

I also try to avoid injecting content into webpages with JS enabled, since that is extremely fingerprintable and opens a can of (in)security worms.

Some addons that I do not recommend at all:

• Canvas Fingerprinting Defender: injects JS into pages, which is very fingerprintable and can trigger a CSP report if you don’t disable those. CSP reports can identify you even if you disable JS execution.

• Anything that you can do without an addon, TBH. They do weaken the browser security model.

In Firefox I have:

• uBlock Origin: For blocking ads
• uMatrix: for blocking all kinds of stuff and to see what kind of connections each site uses (usually a ton)
• HTTPS Everywhere: to have https everywhere. According to @Jojonintendo this is already integrated into Firefox though, so I might delete it.
• Cookie Autodelete: pretty self-explanatory.
• Decentraleyes: to prevent websites from loading unnecessary resources.
• Privacy Redirect: mostly used to open Youtube links in Freetube, but also to redirect Reddit and Twitter links to libredd.it and Nitter respectively, when needed.

uMatrix - To block any unnecessary requests. Js, CSS, etc Https Everywhere - For https everywhere possible Tree style tabs - I find it more comfortable Dark Reader - So that my eyes don’t hurt

• uBlock Origin (obviously)
• Stylus (quick user styles)
• Archive Page (one click archive.today)
• SingleFile (archive HTML pages locally)
• ARIA DevTools (for quick a11y audits)

• vim-vixen make your browser keyboard-oriented (vim keybinding).
• ublock-origin wide-spectrum content blocker (not just ad’s).
• copy-plaintext avoid a lot of garbage formatting.
• privacy-redirect redirect twitter, reddit, youtube, etc to their alternative (privacy friendly) frontends, like nitter, invidious, etc.
• Fedishare to share pages to the fediverse.

I use literally a dozen of them so I had to look at about:addons lol

• Basic JSON Formatter: Installed by default, quite useful to me as I deal with JSON API quite often.
• ClearURLs: remove tracking URL params
• Geminize: open Gemini links in a proxy
• HTTPS Everywhere: helps me redirect HTTP to HTTPS, but it breaks xkcd random button, sadly. I guess I should contact Randall.
• KeePassXC-Browser
• Native MathML: use MathML instead of the JS-rendered for math stuff
• Privacy Badger: Trackers blocking
• Privacy Redirect: redirect links to Reddit, Twitter, YouTube
• Read Aloud: TTS reader, because Firefox’s Reader mode TTS is somehow broken
• Redirector: For redirects that can’t be done with Privacy Redirect
• Stylus: Custom stylesheet, because some websites suck at styling
• uBlock Origin: beside trackers blocking, it also helps blocking sites I don’t want to visit, such as web scrapers or sites that are blocked by my ISP (e.g. medium blogs)

Privacy Badger, uBlock Origin, Dark Reader, and Firefox Relay. I used to have HTTPS everywhere, but now Firefox has an integrated option to do the same.

• Absolute Enable Right Click & Copy
• Amazon Container
• Augmented Steam
• BazQux Reader: open links in background tab
• Bitwarden
• ClearURLs
• GNOME Shell integration
• Google Container
• LocalCDN
• Privacy Redirect
• ProtonDB for Steam
• Purple Ads Blocker (twitch)
• uBlock Origin

I use what the Arkenfox project recommends:

This list covers privacy and security related extensions only. While we believe these are the very best of the best, this can be subjective depending on your needs. We are also not saying you have to use all these extensions.
Extensions (in no particular order...)

• uBlock Origin ✔ Privacy
  

• Temporary Containers ✔ Privacy
    This can achieve almost everything First Party Isolation (FPI) does without breaking cross-domain logins. And (with or without FPI), in a hardened TC setup, this can even isolate repeat visits to the same domain, which FPI alone cannot.
    Required reading: [1] AMO description [2] Article [3] TC's Wiki
  

• Smart Referer ✔ Privacy
  

• Header Editor
    Allows you to run Rules to modify modify the request header and response header, cancel a request and redirect a request. Be careful not to alter your passive fingerprint
  

• Skip Redirect
  

• ClearURLs ✔ Privacy
  

• Request Control
  

• Redirector ✔ Privacy
  

Plus I also use Gesturefy and Behind!

Firefox

• Ad nauseum - like ublock
• temporary containers - this is a must, separates cookies
• foxyproxy - pattern-based proxy redirection. I use it to make .onion and .i2p sites go through specific ports

I use Firefox.

Privacy related: uBlock Origin, LocalCDN (active Decentraleyes fork), PrivacyPossum (don’t have it enabled all the time), CanvasBlocker, ClearURLs (cleans tracking query params).

Convenience: BitWarden, Firefox containers, Temporary containers, Privacy reditect (super handy), ToS;Dr, RES, Stylus and Dark Reader (with the new DR version I sometimes save the generated “dynamic” style after navigating some pages of a website, and then shove it into Stylus for better performance).

Absolutely need this, I don’t even know how to browse without this anymore lol: Tree Tabs (this specific one: https://gitlab.com/kroppy/TreeTabs ; I dislike all others; I also remove the normal tab view at the top with user css) and AutoTab Discard (I tend to open a lot of tabs and without this my RAM goes bye bye; TT has this but it’s not as good)

Additionally, I have a second Firefox profile that I can quickly bring up with Ctrl+Alt+F (akin to getting a terminal) and that sort of emulates Firefox Focus on desktop. Essentially it doesn’t store cookies between sessions, there’s no history, and all tabs are temporary containers. I don’t have as strict rules in uBlock and whatnot in that profile and I often use it for stuff that breaks a lot with my normal setup, or for things that I really don’t want to run on my normal profile (like Google). Also, I enabled DRM in it because some platforms I use require it. I try to minimize that usage though. I even made a little theme for the profile using color.firefox.com :D

Ublock origin, privacy badgers, the containers extension, stylus

I use uBlock Origin on Firefox with Javascript, remote fonts, and all 3rd party resources blocked by default, and I also use Yomichan with several J-J and J-E dictionaries for quick, high-quality lookups and making Anki cards.

I have another profile with no extensions aside from cookies.txt to extract cookies so that I can use youtube-dl for those sites.

And, if you can call it an add on, I use custom search engines for a lot of sites. As for the extensions I don’t use, I’ve disabled and removed the EME and Widevine DRM modules that Firefox ships by default because it’s proprietary and…it’s DRM. DRM is ridiculous and bad, and it only ever punishes people who don’t pirate content. It also empowers monopolies.

On Firefox I use Sidebery which is a modern and very customizable tree-style-tabs-like sidebar extension

I filtered out some that are purely just for web development

• Don’t Fuck With Paste
• Easy Auto Refresh
• EditThisCookie
• GoFullPage - Full Page Screen Capture
• JSONView
• New Tab Redirect
• Pushbullet
• Remove Element
• uBlock Origin