I use Pandora and Spotify and Tune in, and have few issues, but if I ask for a particular artist without specifying the service, it tries to play whatever is in my personal playlist with Amazon (which is truly a small amount of music) and often won't play anything. I suspect, that having Amazon's music service will give you best results through Alexa, simply because it's Amazon's Product, and they will stay on top of it more than making 3rd party services work with their system.