There is always the conundrum of quiet versus airflow.
For a 120MM fan:
The Noctua SF-P12 is very quiet and has decent airflow, however, in terms of raw power you can't beat the LOUD Silverstone FM-121 which can move 110 CFM. For my set-up I prefer a powerful fan that I can undervolt with a fan controller when I don't need a lot of air movement.
In general people rave about Papst fans for silence, but Newegg doesn't sell them. Have to go elsewhere.