Mostly YouTube Music - the recommendation features are much better than spotify's (and it has much better UX). Also regular YouTube suggestions, but I only get jazz and kexp recordings from there.
I used to have a shared playlist with a friend where we'd casually add any cool tracks we'd discover, which was a weird small motivator to discover new music on my own (so that I could show off). Sadly, that person is not a friend anymore, so the playlist is dead.