AdBlock: Block all the annoying blinking overloaded stuff blocking the overview of the website
Ghostery - prevent tracking (Google, FaceBook,...): Because I do not like being tracked. At all.
HTTPS everywhere - always prefer TLS: When all traffic is encrypted, no one knows which of the data is confiential.
Akari Link Shortener: Because long links can be annoying and waa.ai is very cute <3
Stylish - change CSS of any website: I hate all those virulently colored websites. Dark themes are good for the eyes.
Disconnect Search - anonymize Google and other search engines: I do not like getting answers which are filtered specifically for me (Google at least does that)