The most important thing needs to be the communication of the pose. You should choose your poses based on what that pose is saying to the audience. The pose should, in some way, accentuate the emotion or intention of the character, and augment the performance. The body pose should echo the face in most instances (a shy pose with a cocky facial expression just feels weird and confusing), so that's a good indicator as well.
There is no hard and fast rule for this, as sometimes the performance will call for a character hiding their emotions. In these cases, you usually want to betray the emotions in some way, at least to the audience if not to the other characters, through subtle shifts in the pantomime body poses, or through the eye animation, etc.
But in general, my recommendation would be to film your video reference over and over and over, until you are no longer thinking about the actual words of the line, and instead are thinking only about the subtext (what the character means instead of what they are saying) and are actually feeling the true emotions of the characters. If you can get yourself to that place in your video reference, you will discover some very communicative body poses that will take your performance to a whole new level!
Good luck, and have fun!!