What actually separates products, now that quality does not

Almost every product in this category produces realistic headshots. Comparing on realism compares things that no longer differ.

The axis that does separate them

Identity. The output looks like a professionally photographed person who is almost you — a jaw slightly narrower, eyes sitting slightly differently. Nothing you can point at, and yet people who know you notice.

Plausible and identical are different targets, and the gap widens for faces further from the average.

How to test it in twenty minutes

Generate twenty portraits. Mix ten with ten real photographs of yourself and ask someone who knows your face to sort the pile. If they can sort it reliably, the likeness is not there.

That is more informative than every comparison table in the category, and no article will run it for you.

The other real axis

Repeatability. One good image out of forty is luck; forty usable out of forty is a product, and the difference only shows if you generate more than you need and count.