I can't recommend the NF-F12s enough if noise level is what you really care about. I currently have 4 machines in my office; two are 100% noctua fans (7 140mm fans & 5 120mm fans), one has a couple of 80mm noctua fans, and the fourth has 7 SP-120s, two of which only run when the GPU tells them (Asus Strix card). The machine with all of the Corsair fans is the loudest at idle even against the other machines that have all fans running at the same time. Don't get me wrong the SP-120s are excellent fans; they're just louder. If you're looking to make your system quieter, go for the NF-F12.
LTT introduced me to Noctua, and I'm a fan for life.