Apple Music is essentially in fourth place, miles behind Pandora, Spotify, and YouTube, and all the companies ahead of Apple are only getting bigger and better. Pandora, which has 78 million active users, just bought Rdio and has plans to launch an on-demand service late next year, giving its users an in-house option and push it into direct competition with Apple Music. Spotify announced it had 75 million users in June, and expects to reach 100 million users by the end of the month. YouTube — which is easily the largest music streaming service — just launched a standalone YouTube Music app to make it easier to stream audio content.
Source: Apple waited too long to get into music streaming | The Verge