SoundCloud does an excellent job of finding "similar tracks" which autoplay after your current, and I often find myself in the same boat (or bookmarking a track because the related tracks are so good). Spotify comes from the other direction: You can play anything, as long as you know what it is, and the discovery (outside of "Discover Weekly") isn't as on-point or pushed onto you as strongly.

Beyonce doesn't release her songs on SoundCloud, but those who I listen to (or find myself listening to) on on SoundCloud aren't on Spotify.