I would rate SMG a step above SM2 which wasn't even a real mario game. Anyway between the two 64 kicks galaxy's ass. World knocks both of them out of the park though.
Mil. Sellers:
Wii: 25 titles 101.4 mil total avg 4 mil per title
PS3: 14 titles 28.6 mil total avg ~2 mil per title
360: 41 titles 89.8 mil total avg >2 mil per title