Catalog size is an important aspect of subscription services for core music fans. So, who has the largest one of them all? Spotify. As of this month, Spotify has 12.7 million songs in its catalog. Rhapsody is right behind them with 11 million songs and MOG has 10 million songs. The truth is that most casual fans won't be able to tell the difference in catalogs, but when it comes to looking for those obscure, yet wonderful songs, it looks like Spotify is winner.

There's honestly nothing worse than searching for an artist in your music app and finding out that they're either too obscure to make the cut or are like Metallica and others who have decided to opt out of subscription music. Take a look:

(Image via pansentient)