It depends on size and budget, but our go-to for our clients has been the be quiet! Shadow Wings 2 when they can afford it.

be quiet! Shadow Wings 2 120mm PWM Black, BL084, Cooling Fan

Minimal noise and virtually no vibration.

They used to purchase a great deal of Noctua, but started migrating to be quiet! a little over 24 months ago.

They also purchase a number of Silent Wings 3 (120mm PWM, model BL066) when you're attempting to get a cooling advantage without the noise of the Pure Wings 2 Series (which we feel is still quieter than most).

On the budget side, there are plenty of Thermalright TL-C12C fans, and we don't see any more problems out of these than any other fans anybody's buying. They are hard to beat for the price.

But when it comes to projects, Arctic is often first choice. Mostly the P Series, and occasionally the F Series

But in our personal opinion, if it's in your budget, the Shadow Wings 2 is what we would suggest.