Looking at the comments, interest in privacy and adblocking seem high. But the actual addons suggested here are often redundant or even worse, make you easier to track. Instead, take a look at the Arkenfox wiki, which is more or less the gold standard for browser privacy. Both LibreWolf and Mullvad Browser, practically the most privacy/anonymity oriented browsers out there, right behind Tor, either rely on it or stick very closely to it.
I highly recommend reading the entire wiki from the start. You dont have to do everything it says, obviously, but even if you dont do anything it will give you a better understanding of browser privacy. And lastly, do not use Chrome or any chromium based browser if you care about privacy and a free and open internet. Even if you only use a chromium based browser, you help increase googles monopoly.

uBlock Origin

Decentraleyes

Consent-o-matic

These are essential to me. Consent o matic automatically fills out cookie pop-ups by opting out of everything for you. Some of these cookie things take a while to process which shows how devious they are set up

On Firefox:

• uBlock Origin
• Bitwarden
• Decentraleyes
• Terms of Service; Didn’t Read
• Firefox Multi-Account Containers
• Facebook Container
• Consent-O-Matic
• Don’t Track Me Google

…and the add-ons not related to privacy:

• 10ten Japanese Reader (Rikaichamp)
• Zhongwen
• New Xkit
• Earth View from Google Earth
• Palette Creator
• Save to Notion
• Send to Outline
• Web to EPUB

I use most of these on Brave Browser, too.

• Adguard (Adblocker)
• ProWritingAid (Grammar Checker)
• Volume Master (Boosts tab audio)
• Chrome Remote Desktop (Obvious)
• Honey & Rakuten (Coupons and Cashback)

I also use a Chromebook, so I use these “native” extensions I developed.

• CrosKeys (Launcher, Clipboard Manager, Scripting, basically a Rofi replacement)
• CrosPaper (Wallpaper/Screensaver Manager)
• CrosManager (System Manager)

• AdNauseam (for cases when other extensions miss something)
• Bypass Paywalls
• Decentraleyes
• Don’t touch my tabs! (rel=noopener)
• Don’t track me Google
• Forget Me Not
• HTTPS Everywhere
• Old Reddit Redirect
• Redirector (to use the Vector theme on MediaWiki instances)
• uBlock Origin
• uMatrix
• User-Agent Switcher and Manager

I have these extensions pinned:

• uBlock Origin
• Firshot (takes screenshots of website with scrolling)
• Google Translate
• Wolfram Alpha
• Tampermonkey (let’s me write/add scripts to websites)
• Just a clock (I hide my windows startbar so having a little clock always displayed is nice)

And my remaining extensions are:

• Alternate Player for Twitch.tv
• BetterTTV
• Chrome Remote Desktop
• Confetti Snippets (adds copy button to code on Stack Overflow)
• DeArrow (Crowdsourced titles and thumbnails to remove clickbait from YouTube)
• Enhanced Steam
• Google Docs Offline
• HTTPS Everywhere (changes http links to https)
• JSONVue (formats and makes json collapsible)
• Lighthouse (tests website performance)
• Netflix Extended
• Reddit Enhancement Suite
• Refined Prime Video
• Resource Override (let’s me replace requested web resources with local versions of those files)
• Return YouTube Dislikes
• Save All Resources
• ShareX
• SponsorBlock
• SteamDB
• Tab to Window/Popup (adds keyboard shortcuts to between normal browser windows and the popup windows that don’t waste space with a title bar, useful for vertically split window layouts)
• uBlacklist (block sites from Google search results)
• View Image (returns view image option to Google Images)
• WAVE Evaluation Tool (tests website accessibility)

Augmented Steam
Bitwarden
ClearURLs
Cookie AutoDelete
Decentraleyes
Disconnect for Facebook
Don’t touch my tabs!
Enhancer for Youtube
Flagfox
Link Cleaner
NoScript
Privacy Badger
RES
Skip Redirect
Tree Style Tab
uBlock Origin
Undo Close Tab Button
View Image

Firefox:
UBlock Origin
DuckDuckGo Privacy Essentials Plugin
Decentraleyes

Brave:
UBlock Origin
DuckDuckGo Privacy Essentials Plugin

I dont use HTTPS Everywhere anymore because its included in Firefox and Brave!

Edit: I only use Brave to do my school homework because firefox messes with the website we use sometimes.

On Firefox:

• uBlock Origin
• DuckDuckGo Privacy Essentials
• Privacy Badger
• SponsorBlock (skips the promotional parts of YouTube videos)
• Youtube shorts block
• 1Password
• Dark Reader
• Don’t Fuck With Paste
• Facebook Container
• Bypass Paywalls
• Disable HTML5 Autoplay
• Ghostery
• Old Reddit Redirect

Here are the plugins I use:

• React Developer Tools (useful for developing with React)
• Ublock Origin
• Return Youtube Dislike
• SponsorBlock
• Grepper (shows convenient code snippets when I Google stuff)
• Cold Turkey Blocker (I use this to to block websites/apps when I need to focus)
• Shinigami Eyes (highlights queer friendly and anti queer subreddits/users/facebook pages/group differently)

• UBO
• DDG Privacy Essentials
• LocalCDN
• Cookie AutoDelete
• TamperMonkey
• LibRedirect
• Keyboard Privacy

I highly recommend checking out Firefox Multi-Account Containers.

• AdGuard Extra

• AdNauseam (uBlock Origin fork)

• Bitwarden

• Clickbait Remover for Youtube

• Custom Scrollbars

• Don’t accept image/webp

• Enhancer for Youtube

• Proton VPN

• RES

• Return Youtube Dislike

• Sponsorblock

• Thumbnail Rating Bar for Youtube

• Tree Style Tab

• Translate Web Pages

• uBlacklist (no more deviantart trash in image search)

• Redditsave (probably won’t need this anymore since i moved here)

• vidIQ Vision for Youtube (information on screen pleases me)

• Violentmonkey

• Youtube-shorts block

and thanks to the based commenters here, learned there were some userscripts for kbin and got the Dark Reader extension

Here’s my list. Using OperaGX.

• Bitwarden
• Buster
• Consent-O-Matic
• Dark Reader
• FastForward
• Picture-in-Picture
• Stylus
• TamperMonkey
• The Stream Detector
• uBlock Origin
• Session Buddy
• Return YouTube Dislike
• Looper for YouTube

I’m using Firefox:

1. uBlock
2. Darkreader
3. Privacy Badger
4. NoScript
5. uMatrix
6. Bookmark Dupes
7. CanvasBlocker
8. ClearURLs
9. YT Enhancer
10. FF Relay
11. Open in Private Mode
12. Open Tabs Next to Current
13. Secure Password Generator
14. Toggle web custom fonts