Thanks all for participating. I deleted A after saving it for this feature. The head of bird A is pretty much parallel to the back of the camera as many of you noted and this is a fine acceptable head angle (for me) for a perfect field guide portrait with the bird's body also parallel to the back of the camera. Here is the important lesson that nobody picked up on: in both of the images, each created in the same tenth of a second, the bird's body is angled slightly towards us. In these situations, the very minimum requirement is that the bird's head be on straight, that is, parallel to its body. In A the bird's head is actually turned away from the direction that the bird itself is pointed. In B, with the head turned just a bit more towards us, the head is on straight. As many noted, it seems that the bird is more engaged with us. For me, that is caused by the way the light is hitting the bird's face. In A, the face in front of the eye is darker than in B because the head is turned away from us and from the light. Even though it was cloudy, the light still had a direction. My two cents. After commenting on a few comments I will post two more. Good luck! Just to be clear, B has the best head angle.

Note: Thanks to Jon Saperia for correcting the typo above. Glad that someone was paying attention.