All Android phones support Opus which makes it a great format if storage space is limited, as it's optimized for low bitrates. You can go as low as 64 kbps if you are not picky. 128 kbps is near transparent and certainly enjoyable, while 192 kbps is basically a 320 kbps mp3 equivalent.

At 128 kbps, one can store 5000 songs even if they have just 20 GB to spare, as mentioned above.