Noctua, but $20 might not be enough for the cheapest one depending where you live.

I’m not buying anything else and I’m also swapping out any non-noctua fan in my parts when possible (e.g. bought a scythe cooler due to ‘interesting’ dimensional constraints and swapped its fan with a noctua one.)

I always buy the cheapest PWM fans available in a nearby store (so usually Arctic) and I never had one fan fail on me in my life.

They almost never run 100%, though, and I have a recurring task set up to clean dust outta my filters, computers and servers.

OT, but what do you use to manage recurring tasks? I haven't found any solution that I love.

I tried using different sd cards with RPi but kept having issues with broken filesystem few months after, it was probably caused by bad power supply and electric surges.

You don't HAVE to boot RPi4+ from an SD card. RPi4 and RPi5 can boot from an external SSD just fine. I don't recall the last time I used an SD card in an RPi but it must have been years.

Yeah, that's what i have done, but it becomes bulky which doesn't always fits the project