Just Firefox/Librewolf with uBlock Origin is enough. The more extensions you add, the larger the attack surface and chance of site breakage. A common mistake many do is to add multiple blockers on top of uBO which will decrease uBO's ability to defuse various anti-adblocks. This also includes addons like Privacy Badger, Ghostery, DuckDuckGo Privacy Essentials, etc. uBO have good enough privacy protection enabled by default. If you want more, enable some other privacy filter lists. And if you know what you're doing, enable hard mode by blocking all 3rd party requests and JavaScript.

If you want to feel more secure when adding more extensions to your browser, then only use Firefox addons that are recommended by Mozilla. Those extensions have gone through a review process to make sure they don't contain anything malicious.

If you're like me and don't care about recommendations and being able to comment, then use Freetube with sponsorblock enabled.