Hacker News would be mine, the amount of time wasted on that website in insane (tbf I'm interested in tech and programming), thank god for their noprocrast option.
YouTube, with a watch later playlist. I heard on fedi that YouTube's recommendations are absolute garbage if you use an adblocker. I don't know how true it is, but if it is it explains why I've transitioned to using Watch Later.
The fediverse instance I use that's solely for microblogging.
Rate Your Music. Probably my favourite music site right now, and one of the few sites I've given money to. It's great for discovering new music that you'll love IMO. It's been going on for a couple decades now, definitely worth having a look.
MusicBrainz, which is basically a giant encyclopedia of music releases for computers to use. I've added releases to MusicBrainz from stuff I've bought. If you've used MusicBee, MP3Tag, or their own tagger Picard, you've used MusicBrainz. I've since replaced Last.fm with ListenBrainz since the data quality on the latter is much better than Last.fm.
Just plain old YouTube, I do have to delete all my watch history now and then so it doesn't start recommending low quality videos.
Oh and ublock and sponsorblock are a must these days.