Quote - The original figure, on the left, has a strange side turn in the right buttock. The WM figure does not have this streak, but buttocks still look a bit like they are 'glued together'. 

With arms up further up on the shoulder, next to the neck, the original figure shows the rise of the muscle, where the neck/collar area of the WM figure, on the right, looks too low and the neck points out oddly.

Based on what I have seen here, I would say both Antonia 1.2 and the weight mapped versions have their strong points and their flaws. Knees and elbows look better in the JCM version. Buttocks look better with weight mapping. The situation next to the neck is a bit ambiguous. Issue becomes serious fairly extreme arm lifts. Clothing will be behaving there very different from the skin anyway. 

If it is for ease of fitting clothing, I would think a hybrid Antonia would be worth considering. Thigh area is a prime source of trouble, not in the least because it is the area mostly covered by clothing. Also, there is the interference beteen left and tight thigh, and 3 for each connection axises of rotation to deal with. Bending at elbows and knees is more simple. They have only one axis of rotation that matters and part of a simple chain of members.

My bet would be body, shoulders and thighs weight mapped, and keep JCM's for knees and elbows.

Arms/neck area must looks weird, because it is impossible to raise arms this way. Even if you create perfect JMC or WM it will looks unnatural. Human can raise arm about 20-30 degrees and it deform almost whole chest and back. If you try rise your arm (not Antonia's), you must according to Poser setting - twist collar and swing arm.

Few months ago I've tried to change V4 bones setting joint center of collars in the middle of chest. I wanted to make bone which deform chest, but it was too difficult. In adult magazines you can see that models very often rise arms. It lift breasts and makes them less saggy. Anyway it shows how big part of human body is deformed by raising arm.

To be honest most of rigging should have additional JMCs. Sometimes quite far from joint. For example bending thigh deform back of knee and calf. Bending elbow is impossible without bulging biceps etc. I think it is impossible to create natural rigging system in Poser. Before you finish one figure they create new Poser version with new rigging :)

Now I'm going to check with my wife which buttocks looks better :)