MP3 vs AAC (M4A)

I'm really curious about this. I know M4A files are smaller, but... which one sounds better? I'd like to know which of the two sound better at lower / higher bitrates too. I'd really appreciate some actual technical knowledge on this... although you can go ahead and say what you've heard personally.

I know a lot of the folks here pride themselves in their VBR MP3s, and to tell you the truth, I'm one of them. I've been ripping in VBR for years and years. But I'd still like to know about this. If M4As sound better, maybe it's time for me to switch considering the smaller file size.

EDIT: Actually I just took 3 different songs and made 128 kbps versions of each format and a 320 kbps versions of each format for all 3 songs. One song was 2:00, one song was 3:45 and one song was 9:30. The MP3 was smaller every single time, with as much difference as 400 KB. So basically, I'd like to know which sounds better, and why the hell MP3 is smaller, lmao.

How ya doing, buddy?

At higher bitrates the difference may not be obvious, but at lower bitrates, I find that AAC handles the sound much better than MP3, especially when it comes to transients. AAC encoded songs do not suffer from artifacts such as pre-echo nearly as much as MP3 encoded songs.

There's nowhere I can't reach.

Cool, because I'd had a feeling that was true for the way AAC handles lower bitrates. Although I'm less interested in them, still good to hear someone else say it.

This thing is sticky, and I don't like it. I don't appreciate it.

I was under the impression Ogg was king of low bitrate audio. Or is that thinking two or three years past its due date?

I am a dolphin, do you want me on your body?

In blind listening tests, Ogg, MPC and AAC score roughly the same at low bitrates.

I was speaking idiomatically.