Thought this was an interesting table for those thinking about changing fans.

https://www.quietpc.com/120mmfans

Lists, RPM, dB, airflow, price etc.

E.g. the Scythe Slip Stream 1900 is the second cheapest, best airflow, and not bad acoustic rating.

Think this is what @blissz has? Think I will get some and try them out. Don't look massively amazing from photos though!