Choosing a physical personality in character creation would be nice.
A lot of work, but it would be amazing. Choose "shy" for a timid body language, "confident" for something like this hero pose, "aloof" for frequent "arms crossed" or the like. It could make a lot of difference with the focus on cinematic dialogue and how there's currently not many ways one can convey a custom character's personality other than choices.
I don't think it would require more than a few poses?
For "character stands in a conversation" - yes, but I had in mind a different body language in general - so more animations. Should have clarified that.
My biggest problem during conversation is my evil character freaking out over every small hint of violence.
Hated this as well, if 5e had alignment it would be easier to just encode different reactions for Good, Neutral or Evil characters.
I think a personality tag system would work better, though again, admittedly more work. A good character could be stoical and freak out and an evil one could dislike violence when it happens close to him.