What is the best 140mm Noctua fan to use as a case fan

Solution
There are three Noctua's in the top 5 in the test here, they came in 2nd, 3rd and 5th:

http://www.silentpcreview.com/article1345-page7.html

1. Phanteks PH-F140HP/TS .... $15 http://www.newegg.com/Product/Product.aspx?Item=N82E16835709023
2. Noctua NF-A14 FLX ..... $25 http://www.newegg.com/Product/Product.aspx?Item=N82E16835608034
3. Noctua NF-A15 PWM..... $27 http://www.newegg.com/Product/Product.aspx?Item=N82E16835608036
4. Noiseblocker B12-2
5. Noctua NF-P14 FLX .... $29 http://www.newegg.com/Product/Product.aspx?Item=N82E16835608017

I use the Phanteks as both case and radiator fans.....perform a bit cheaper (little more air and a litle more quiet) and 60% of the cost
There are three Noctua's in the top 5 in the test here, they came in 2nd, 3rd and 5th:

http://www.silentpcreview.com/article1345-page7.html

1. Phanteks PH-F140HP/TS .... $15 http://www.newegg.com/Product/Product.aspx?Item=N82E16835709023
2. Noctua NF-A14 FLX ..... $25 http://www.newegg.com/Product/Product.aspx?Item=N82E16835608034
3. Noctua NF-A15 PWM..... $27 http://www.newegg.com/Product/Product.aspx?Item=N82E16835608036
4. Noiseblocker B12-2
5. Noctua NF-P14 FLX .... $29 http://www.newegg.com/Product/Product.aspx?Item=N82E16835608017

I use the Phanteks as both case and radiator fans.....perform a bit cheaper (little more air and a litle more quiet) and 60% of the cost
 
Solution