Don't know if anyone else looked this review thoroughly but there seem to be clear conclusions which can be drawn from it.http://www.hardware.fr/articles/874-1/comparatif-63-ventilateurs-120mm-dc.html
While fancy blade shapes and surface textures might sell their effect to noise seems to be mostly negative with possible resonances at certain speeds.
Zaward Golf (ball) Fan is one example.
Then Zalman ZM-F3... And Noctua P12 is no surprise.
And then comparison between SlipStream and GlideStream.
Also brittle bling bling plastic has obvious effect.
Xigmatek 1254 has quite spiky curve and also Nanoxia lacks smooth curve despite of standard blade design.
And all Enermaxes have spiky curve...