I've given this question a lot of thought in terms of how it should work for me specifically, actually. And what I've come up with is this: because the kind of fiction I write is aimed at putting the reader as inside the point-of-view character's head as immersively as possible, it always depends on what the character would really tend to be thinking at any given moment. So with a really self-aware character, you'd get a lot more "telling" than you would with someone who is in denial of their emotions and mental states, but even there, "showing" is usually going to be more representative of the inside of someone's head.

-J