Aside from mattermark daily, I've haven't found a single newsletter that has had consistently good material. Tried several, but kept unsubscribing when they started to feel like spam.
I found some of the human-made playlists on 8tracks.com to be better than a lot of the algorithmically generated ones on Pandora/Spotify/Youtube, but music is highly subjective.
Been meaning to give product hunts collections a solid attempt:
https://www.producthunt.com/collections
For book recommendations, I find an intellectually-minded friend on Goodreads who has similar tastes to me, and just go down his/her list.
I think a general pattern here is: there are positive deviants in society whose tastes and interests correlate with my own far stronger than the average's.