Quiet isn't really my thing, but to my understanding both of the following are decent in that regard:
High-end air: Noctua DH14: http://www.newegg.com/Product/Product.aspx?Item=N82E16835608018&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
High-end closed-loop liquid: NZXT Kraken x60: http://www.newegg.com/Product/Product.aspx?Item=N82E16835146028&nm_mc=AFC-C8Junction&cm_mmc=AFC-C8Junction-_-na-_-na-_-na&cm_sp=&AID=10446076&PID=3938566&SID=
Edit: One of the features reviews (particularly for the Kraken, although I believe I recall seeing it in one for the DH14) highlighted was the ability to beat most coolers on max while running in on quieter speeds. As a result, unless you need them at max capacity, I believe that either should be decently quiet.