Any GSkill Ripjaws or Corsair Vengeance or really any quality band with a lifetime warranty ( Crucial, Samsung etc. ) is fine. If you get the Corsair make sure it's the low profile version if you plan on adding an aftermarket cooler.
You want 1.5v DDR3 1600 cas 9. Anything faster is a waste of money on a Sandy Bridge chip due to the integrated memory controller not being able to use it. Going over 1.5v voids the CPU warranty.