I’m considering doing some fan editing on Avatar The Last Airbender.

There are two sources I can choose from, both come from Blu-ray 1080p H.264
But they have different bit rate and different audio.

One has a bit rate of 5760, but the audio is only stereo audio.
The other has a lower bit rate of 1635, but the audio is 5.1
Logic tells me that having 5.1 audio would make for a better experience.
But how important is it to have a higher bit rate? Does it matter that much for animated content?

I can’t visually tell these sources apart.
So how do I pick which source to use?