The Corsair Hydro has an excellent reputation. It is on the pricey side though.

You might also want to consider this one - I have recently installed it on my overclocked i7-920 rig after my watercooling unit packed up, and the temps are only slightly worse than watercooling. I have been extremely impressed with it, and I thoroughly recommend it

http://www.arctic.ac/en/p/cooling/cpu/3/freezer-13.html