I own a Z3 and a Combustion 5. Not exactly the same as an AB, however, the body shapes are.
No doubt a Z3 neck profile is thinner. For me personally I like that better than the thicker profile necks. But I can see how some would like a thicker neck better. The Z neck is really thin. That is all personal preference though. Similar to how some people like P-Bass necks better than J-Bass necks. One other difference between the necks is that the Z uses a tilt-back headstock whereas the AB's use a straight headstock with sunken tuner posts. Here you can see the different profiles and headstocks:
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I DO like the thinner more curved/rounded body of the Z better. Super comfortable.