There's really no point in more than 1 5/8oz of the 9s. It doesn't matter which one you choose. There's just so many pellets you're sure to get a pattern together. Why?
2oz is extreme overkill. That's almost twice as many pellets as a 2oz load of lead 5s. I would not be surprised if that load would hold a pattern further than those pellets will kill. In fact, as I know how far my 20ga loads will hold a pattern, I'd bet on it. So you're buying and throwing shot that doesn't accomplish anything.