I see brown fans and I think someone paid over the odds for two bits of injection moulded plastic and an electric motor. And still ended up with brown fans.
Barring incompetent designs all fans run on the same basic principles of rotation speed = noise = airflow and pressure.
The ONLY thing Noctua brings to the table is the colour brown.
I think Noctua were the people to bring us fluid bearing fans, and even now not many other companies seem to do them. I find them much quieter, and they never wear and get noisy like fans with ball/sleeve bearings eventually do. They don't have that slightly buzzy sound quality that ball/sleeve fans often do. I've had some going for ten years that are still quiet and efficient.
Yes the colour is silly, but if you can get past that or if you can't see the fans in your case, they are really excellent.