More than likely Sony is probably going to have more units. Given what we know MS probably is probably going to have a bigger chip which means Sony will have a yield and chip volume advantage per wafer.
And Sony is a CE company who launches way more hardware products than once ever 4-8 years. This is where Sony should have a definitive advantage here.
Unless Sony has lost its touch, I can't imagine MS having more units.
It also depends on the scope. Sony should not be launching with 3 OSes as far as we know.