Great work. The third one has great exaggeration. You could keep the cheekbones and the nostrils a bit more symmetrical in all the drawings.

It's easy to get tripped up thinking a lot about what the average face is. But don't put too much stress on it. It's not so much a scientific anatomical principle but rather a personal psychological construct. I think it's true, that, in general, most adult peoples' heads tend to follow the rule of thirds on the face (equal spacing from hairline to brow, brow to bottom of the nose, bottom of nose to the chin) and some other common qualities like the distance between the eyes being one eye width apart. And you can rely on a few of those big picture concepts when thinking about what to exaggerate. But what is more important than the "average head" diagram is your own personal gut feeling about what average means to you. For me, the average face is the average sum of all the faces I've ever drawn. I started as a live theme park and party artist and have drawn a hundred thousand people or more. So I have a pretty big reservoir to draw upon. The more faces you draw, the better your internal library of faces will become that you can base your exaggeration choices on.