I'm shooting a PMII right now, but if I were in the market for a new scope today I'd probably end up buying the ZCO. The glass is a bit nicer and the elevation range is enormous. The only thing I would miss compared to my S&B is the T3 reticle, but I know how polarizing it is and the other options from ZCO are still quite nice. With new prices being roughly equal between all three of those scopes it's a no-brainer to buy the ZCO in that scenario.
If I was buying used, though, then it becomes more of a debate. The PMII can be had for such a good price here and in other used markets, while the ZCO remains much closer to retail pricing. The ZCO has the advantage of a lifetime warranty vs 2 years (probably already expired) for the Schmidt, but both scopes are made well enough that it doesn't make or break the deal for me. I've dropped my 25+ lb rifle onto my scope multiple times by accident and it still performs flawlessly, and everything I've seen says the ZCO is equally a tank. I'd probably buy another Schmidt personally if only because I can then spend the $600-800 price difference on reloading components, a barrel, or just more guns, but if the right price on a ZCO popped up first I'd probably end up with that instead.