If you just want max airflow, the Noctua Industrial PPC fans are pretty insane.
If you want the best balance of quiet vs performance, then the standard Noctua range are about the best.
If you want some semblance of quiet, plus RGB, but still with bloody good airflow then go with Corsair's ML series.
Just my opinion based on my experienced, YMMV. The biggest factor (in both noise and airflow) tends to be whether you have particularly tight mesh, filters, grilles or radiators up close against your fans, or not. Recently I simply removed the metal grille from the intake cover of my case (Enthoo Luxe) and within a minute my loop temperature dropped by just over 5ºC!!