Better take tongue and groove boards. They are vapor permeable and also look nicer. A few more screws...
I really fell off my chair last week when I wanted to buy the tongue and groove boards + substructure. Admittedly, I didn't do a price comparison and bought it at the nearest hardware store because I needed the stuff on short notice for the weekend.
However, at the first gathering in the new house, I will probably have to show the gilded attic so that anyone even sees it.
On the topic "looks nicer": For the unheated attic, I was told several times not to use OSB at all, as it would otherwise mold underneath. That’s understandable since OSB acts like a vapor barrier and there is also a vapor barrier under the insulation wool. For the insulated attic, I would probably have chosen OSB as well.