YouTube is excellent. Aside from my main account I have one that I mainly just use to listen to music, and I just surf the algorithm listening to whatever is in the recommend list, which is usually a handful of songs I've got on heavy rotation, but YouTube also tends to cycle back some old favorites, and some new gems. I just keep surfing it day in day out letting it take me where it will as one of two main ways I listen to music. I regularly find new gems pretty reliably. All the gems then go to my playlist in Spotify, which I listen to during my commute.

I’ve had good luck with gnoosic. Or taking artists I like as a starting point and finding out who influenced them, and who they influenced.