Is higher bit rate more important?

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?

Bitrate gives an encoder the ability to make a better-looking encode, but there are factors that could cancel that advantage out. For example, people tend to like to DNR animation into levels of oblivion even the worst live action video never sees, so if that’s the case, the high-bitrate advantage in encoding fine detail goes away. If in doubt, high bitrate is usually better though. If you’re comparing images, compare still images of the same frame blown up to a large size, so that you’re not limited by your display size, or where your eyes happen to be focused at that point in time. Look for common video artifacts, edge enhancement, loss of fine detail, that sort of thing.

I’d personally pick the higher bitrate unless it looked worse (which it could: DNR, color issues, etc), because you’ll eventually be re-encoding anyway, which will lose quality.

Properly done 5.1 is nice, but 5.1 upmixes from stereo mixes are not. Find out what he original audio format is for your show and go with that. If it was produced in stereo, you’re almost certainly going to get a better experience with stereo. If it was originally done in 5.1, go with that. You’ll likely need to talk to people who know a lot more about the show than me to get those answers though.