Gesture vs Lip-sync
Here’s evidence that proper acting and gestures are more important than lip-sync.
(It’s a clip Pete Docter showed in a lecture a couple years ago.)
It works really well and makes me laugh every time.
So make sure your character’s body sells the line before you go crazy trying to get the lip-sync right.
-Jacob

OMG, show this to anyone who sits down to draw with animation in mind! Short, right to the point, and FUNNY!