Adblock Plus, Ghostery, and Hush on macOS.
(/rant)
I know this it heresy to say on HN, especially coming from someone who whines about gov surveillance as much as the next person, but I personally love YouTube's recommendation system. And I know from experience it uses what you actually spend time watching to make recommendations (not just what you click on). So I'd personally miss having them be able to measure that...
I feel like YouTube knows me better than any other service I use (besides maybe Spotify which also measures what you actually listen to) and I pay to be a YT subscriber so I don't se ads on iOS mobile (jailbreaking doesn't provide with me ROI).
I hear a lot of HNers complain YouTube recommends conspiracy or negative politics stuff (see: Twitter and Reddit for that who also completely suck at recommendation systems despite aggressive analytics) but to me it sounds like a) they don't actually use YouTube often enough to tell it what you want or b) they are using blockers/not logged in so it can't learn what you like.
BUT THAT BEING SAID, getting to use a minimalist <video> tag sounds very nice otherwise.
I leave Safari as my default browser, although I actually use it the least. But I like having the same "default" experience on my desktop and phone. If I am opening a link from Mail.app or punching something into Alfred it will open in Safari. I use some light ad-blocking. I use Chrome for work. I use Google Translate a bit and this works extra well in Chrome. Plus, Google apps and whatnot. Limited ad-blocking because I'm often using ads platforms. I use Firefox for all my intentional/casual browsing. Maximum ad blocking.