With 2 RAM sticks most coolers will work fine. Tuniq Tower Extreme, Noctua DH14, Prolimatech Megahalem, Scyth Mugen rev B, Zalman CNPS10X Extreme are all pretty good. (I'm using the Zalman, at 177 base clock, with turbo boost enabled, max temps are 70C)
There's plenty of pretty good ones, you can find reviews by googling. Frozencpu.com is a good place too.
Also, H50 or H70 aren't bad, same with CoolIt ECO or Vantage. They generally aren't as good as custom WC loops tho. Mostly on par with a good air cooler from what I've seen.