Lip Syncing
I think the first one looks good and the second one looks better mostly because of the stash movement... Really it's all about making it look believable, because people will imagine it looking right, pretty much as long as it's open when it should be open and closed when it should be closed, just like in animation you can get away with a few key frames and rotating and skewing in between. I don't think Jeff even uses that many mouth movements in tankmen... for something like a small collab part it might make more sense to spend more time on the lip sync, when for something like a 3 minute comedy sketch it would take way too much unnecessary work.
</jumbled opinion>