Which is better Plywood or OSB?
Hard to say one is better than the other. Properly applied, and the proper grade selected for the situation, they are comparable. Generally, plywood exposed to constant moisture will fare better, but neither material should be allowed to soak up water. As far as strength, both will be adequate for home construction (again if installed properly.)
I believe that currently more OSB decking is being manufactured than plywood, an indication of the acceptance of the material. (That, and the slightly lower cost.) Also, in using very small pieces of wood, OSB is an effective method of conserving trees.
I guess the Advantech floor T&G material is considered OSB board and I can personally attest to its toughness. I used it to build a doghouse and never got around to putting on any roofing materials or painting it. It has set outside fully exposed to all weather conditions for 3 years with little damage only slight edge swell. Dont know about the other OSB board materials but THIS IS GOOD STUFF.