hmm me I'm gonna throw a curve ball my favorite would be symmetric but like the left XB pad stick.... because it is not whether it is the correct way or not.... this the most natural orientation of the thumb....
the right stick on the xb pad is bit off... but still better than the DS... so overall the XB sticks are 75% perfect even though asymmetric... while the DS is 50% perfect because symmetric but just completely unnaturally placed...