With Antonia when the head or neck is yRotated (Twisted) it causes head to point skywards (this also happens with the V4 head, but not the neck). I can see why this joint set up might help to get better bending at the neck joint. However I find it can be very frustrating to have to make big adjustments to zRotate and xRotate every time I use yRotate no the head or neck, and especially if I am just experimenting to see what different head rotations look like.

Another thing with rotations of the head and neck is that they usually need to go together. To get a good looking head rotation you need to put some of the rotation in the head, and some in the neck. Also when a person looks to the side, I think that some of the rotation usually comes from the chest, abdomen, and hip.

I have come up with a pose file that uses ERC to help address these issues. It's not a perfect solution, but I feel it goes a long way towards reducing the amount of dial spinning you need to do when getting Antonia to look in different directions. I have called the pose "TwisterAP", it's based largely on an idea from English Bob.

What does it do? It adds the following four dials to the Body.

"TWISTER"
This dial will twist (yRotate) the head, neck, chest, abdomen, and optionally waist.

"Twister_Chest-Abdo_Inc"
This dial is set to "1" by default, setting it to "0" will exclude the chest and abdomen from the twisting.

"Twister_Waist_Inc"
This dial is set to "0" by default, setting it to "1" will include the waist in the twisting, and also apply a small xTranslation to the waist. You need to set leg IK on before enabling this option.

Like I said, TwisterAP is not a perfect solution. The head is not kept perfectly level at all angles of rotation. Between zero and 45° the head can adopt a very slight upwards tilt, over 45° the head adopts a progressively greater downwards tilt, which can amount to about 4° when Antonia is looking 90° to the side. Never the less, I think this a an improvement on just rotating the head and neck in the normal way which results in a very large upwards tilt. Note that as the file works via valeParm channels in the BODY, the influence of TwisterAP will not be saved in a normal pose file.

In the above animation the figure on your left is the standard Antonia with 36° rotation applied to both the head and neck. The middle figure has approximately the same amount of rotation applied via TwisterAP, but with chest, abdomen, and waist excluded from the twisting. In the figure on your right, the chest and abdomen have been included in the twisting. Two of the figures have props parented to the neck and chest to make it easier to judge the amount of tilt.