HELP! Noctua or Gentle Typhoon?

Hi guys, I currently have an Antec 920 Kuhler on my CPU and wanted to replace the fans on the radiator.

I've heard great reviews on both the Noctua HF-P12 and the Scythe Gentle Typhoons 1850rpm (120mm fans) but can't decide which to get ! Which of the two is better ?

Cheers guys