Zalman Z9 or Z11 or Antec 300

So for my new gaming rig which I have already posted in the forums, I am still wondering on what case to buy. I originally picked the Antec three Hundred, but i recently came upon the Zalman Z9 and Z11. Which of these cases is overall superior and which would work best with mild overclocking of an i5-3570k.
In addition to the case I was also planning on buying the Cooler Master Hyper 212+. Is that still necessary for overclocking in addition to 4 stock fans?

Any feedback is greatly appreciated!