Streaming audio is about balance: sound quality, file size, bandwidth, battery life, and whether the listener's device can actually play it.
For most end-user audio streaming, AAC is the best default. It sounds good at sensible bitrates, works across phones, browsers, TVs, and apps, and is more efficient than older MP3 in many cases.
But there is no single perfect streaming format. The right choice depends on whether you are streaming music, podcasts, video audio, live voice, or archival-quality files.
AAC is usually the best practical choice. It is efficient, widely supported, and commonly used by major platforms.
Opus is excellent for speech, live communication, and difficult network conditions.
MP3 remains the safest option when you need playback on old devices, car stereos, or unknown hardware.
The format matters, but bitrate still controls how much data the stream has to describe the sound. Too low, and compression artifacts become obvious. Too high, and you waste bandwidth without much audible benefit.
For the bigger picture, see Audio quality explained: what actually matters?
Lossless audio such as FLAC or ALAC preserves the source data, but it uses more bandwidth and storage. That can be useful for premium music services or home listening, but it is not always necessary for everyday streaming.
In noisy environments, on small speakers, or over Bluetooth earbuds, a well-encoded lossy stream can sound extremely close to lossless. Wireless playback also depends on the Bluetooth codec used by your device and headphones.
Use AAC for general streaming. Use Opus for low-bitrate voice or real-time apps. Use MP3 only when compatibility is more important than efficiency.