I prefer the look on the left. The knees are soft, there's a slight flexion of the metatarsals at the ball of the foot to create an endpoint of tension to trigger more fluorescence through the legs. The arms are straighter. The head is higher to take more strain off the neck. This allows the eyes to focus on the axis running through the hips.

I like the lines in the image on the right, but they come at a cost. The straighter legs and pointed toes makes it much more difficult to find the uniform usage of muscles that we're after. The position of the head looks good, with focus out towards the toes, but this takes more neck (SCMs) and expands the focus.

To the image on the right I'd say: "Legs lighter. Soften your knees. Press out through the balls of your feet. Crease more at the sternum. Look to your hip axis."