I'd go with whatever has nice thick spokes. Xi has jacked up suspension, fat rim spoke will offset that nciely. Dont get deep dish as well. M6 reps sound like nice wheel, but id go for full silver, not black-silver design.
'14 Black F11 530xd - NOW
'07 Silver E86 Z4 Coupe 3.0si - SOLD '16
'07 Blue E90 325i - SOLD '12
'06 Silver E90 320d - SOLD '10
'98 Blue E36 320i - SOLD '06