I use Google Music exclusively, and would rate it the most accessible of the music apps (Spotify, Deezer, etc). It works perfectly on Firefox or Chrome with NVDA. I'm not sure how it works on other screen readers or browsers, because I don't use them. On IOS, it works almost perfectly, with two major issues. The first issue is that it can't always scroll propperly through long lists of songs. Lists of artists and albums, for example in your library or search results, work just fine. But as soon as you get into a playlist, album, or anywhere else displaying a large list of songs, voiceover will scroll through the first 10 songs just fine, and then jump up to the top of the list. To get around this, you're going to need to start the first song playing, and then use the next and previous buttons in the player to skip through the list. The second issue...may not be an issue, per say. What Google has done, in order to make the player more accessible, is whenever the player screen is open and it transitions to a new song, Google tells Voiceover to focus on the title and artist of the song and read it out. Yeah, that's kind of a cool feature. But the problem is, if your focus was on, for example, the next button, after the song changes, Google Music has "helpfully" changed the item you're focused on back to the title and artist currently playing. You're now going to need to swipe back over to the next button again. If you have a headset, this won't bother you at all; just use the next and previous buttons on your headset. If you don't have a headset with next and previous buttons, the best thing to do if you want to skip through songs quickly is to lock your phone, and then use the next and previous controls on the lock screen. When you tap next on the lock screen, you stay focused on the next button, so can tap it multiple times quickly. Useful if you need to play song 36 of an 80 song playlist.

There is one other issue that might affect you, but if you have sighted help for initial set-up, it won't be a problem at all after that. In order to upload your music into the cloud, you need to download the google music manager. Unfortunately, that app doesn't work at all well with a screen-reader. In order to get it working, you'll need a sighted person to install the app, log you in, and point the app to a folder on your computer where you store your music. But once that set-up has been done, Google Music Manager will watch the folder for any new music you add, and automaticly upload it. The app even starts at boot. So just get someone to set it and you can forget it. If you want to check on how it's doing, you can find it in the system tray and click on it, and NVDA will read the progress (something like "895 songs uploaded of 1426"). It hasn't ever broken or had any issues since the first time I set it up, so it's never been touched. It uploads automaticly, and keeps itself up to date, without needing any input from me.

To tell you the truth, I actually did set Music Manager up without sighted help, just by randomly banging on it. I think what I wound up doing was typing my email, pressing tab, pressing enter, typing my password, pressing tab, pressing enter, pressing tab a couple of times, then space, then an accessible "brows for folder" thing opened, and I pressed enter on the folder where I keep my music. But it took me an hour or so of fiddling to get that figured out, because NVDA offers no feedback at all during the sign-in process. Fortunately, the only thing Music Manager does is upload music. So once it's uploading, you never ever need to touch it.