Any of these would do. I personally use Corsair H series.

http://pcpartpicker.com/product/RH2rxr/corsair-cpu-cooler-cw9060027ww
http://pcpartpicker.com/product/bqBrxr/nzxt-kraken-x62-liquid-cpu-cooler-rl-krx62-01
http://pcpartpicker.com/product/2z7CmG/cryorig-cpu-cooler-a80

This one could be interesting too. Rated pretty amazing
http://www.tomshardware.com/reviews/id-cooling-frostflow-240l-closed-loop-liquid-cpu-cooler,4371-2.html

Be Quite Dark Knight 2 or w/e isn't bad. Get a Megahalems Rev. B. and go old school. http://www.prolimatech.com/en/products/detail.asp?id=155