If you start down the quiet path, you will never get to the end.
What is your graphics card?
That may be your greatest noise maker.
Noise comes from fans running at high rpm.
On your case, I think the optimum would be to use two front 140mm intakes running at 900rpm.
Noctua makes good ones like this:
https://www.newegg.com/noctua-nf-p14s-redux-900/p/N82E16835608062
If in doubt, buy the faster 1200 rpm version and plan on slowing it down if necessary.
Keep the 120mm fan as a spare, it is not needed.
If you installing as a top exhaust just because you have it, it will only add to noise and will disrupt the
airflow to your cpu cooler.