ZIP is better then both by a huge margin.
When comparing brand new half inch construction grade, three layer plywood to OSB, there will be no performance differences between the two, which is why OSB meets Code. OSB varies in price during the year, from less then $7 to twice that much. Half inch plywood is going to be $15 to $18 pretty much year round. 1/2 inch ZIP is going to be $20 a sheet plus another $28 for a roll of ZIP Tape. I would have to double check, but I think the green half inch ZIP System goes on 16 inch centers and the Red 5/8's ZIP System goes on 24 inch centers. I don't know what the 5/8's costs. With ZIP System on the roof, you don't need roofing paper.
ZIP is a very high grade of OSB. It cuts clean and you never find any voids in it. You can also buy ZIP Panels longer then 8 feet. I've bought 4x9 and 4x12 for walls that I wanted to avoid a small piece or to run it from sill plate to top plates, and from sill plate to the peak of my ridge. This increases the strength of your wall sheathing tremendously!!!
OSB and Plywood require clips if you have 24 inch centers for your rafters or trusses.
Both brand new OSB and Plywood will hold the nails in place just fine. The nail has to go all the way through the OSB or Plywood. The point does not hold the nail in place. The shaft is what holds the nail in place and it needs to be longer then the thickness of the shingle and the OSB or Plywood. 1 1/2 inch nails are the smallest that should ever be used on a roof. Crooked roofing companies will try to use shorter nails to save money, but just like using staples, this leads to failure.
The biggest difference between plywood and OSB is that during nailing, plywood will blow off that bottom layer of material. This is very common and something that I see when I'm up in an attic all the time. I've never seen it so bad that it's the cause of failure, but it is dramatic enough that I will never use Plywood for roof decking. When that bottom layer is gone, you will often see that there is a huge void there too, so the nail is only being held in place by one layer of material, or a third of half an inch. What is the math on that? For me, OSB is far superior to Plywood on this issue.
Something that I see too often in houses, is people having half inch sheetrock on their ceilings with 24 inch centers. This leads to sagging and even cracking in the ceiling over time. 5/8's sheetrock has to be used for 24 inch centers. With a fairly smooth texture on the ceiling and paint with a little bit of reflection, this becomes obvious. This is also why flat paint and thick texture, like popcorn, was so popular for so long. It hides the imperfections that come from using half inch sheetrock on ceilings.
