For me, it stops being too much at 3D

But that's a boring answer... In the OP pic, 52kg is the last one that doesn't look too fat, but even 40kg one has too huge b00bz. 52 and 47 ones here look basically teh same as each other, from there on girls have their legs touching each other, which would probably also result in a putrid monkey smell. But enough about 3D

In 2D, I still prefer the flattest, but my brain automatically accepts any of the miku in the pic related