A quiet 90 CFM fan isn't possible. Also, everyone knows Silenx rates their fans incorrectly. Put them on a heatsink/radiator and they perform even worse.
Yate Loons are a good value. If you go this route, go buy them from Petra's. They order direct from Yate Loon, whereas others go through a middle man and get knockoffs that use a 80MM motor instead of a 120MM motor.
Scythe S-Flex fans are also a good choice. Don't go over 1200 RPM if noise is a concern though.
For open-air case fans, Scythe Slipstreams are very good. However, they do not have very good static pressure, so things like fan grills, filters, heatsinks, etc. cut down their airflow a lot. Would only use in spots where airflow isn't obstructed.