I prefer plywood because my brother bought an apartment in Vancouver. The building used OSB. All the tenants have water damage to the insides of their walls. I have heard of many stories of leaky condos in Vancouver and I never really thought much of it until I went to see my brother in Vancouver. His apartment has a musty smell and his leaky walls are clearly visible. HE and the other tenants were told that they would have to each pay about 8 to 12 thousaand dollars each to fix the problem. The damage was partly due to the floors expanding allowing water to to seep in further. I have never heard of this happening to plywood as water is able to dissipate faster from it. I know that osb is much cheaper than plywood but it is stands of wood glued together. Water enters mostly through edges especially if untreated in OSB. If you must use OSb you should spend extra time to assure that moisture has not entered before construction and that moisture will not enter. South eastern areas are affected mostly as well as Vancouverites. Plywood is better and CEMENT rocks , see ya !