Ok, I got a Stacker 831 and I have also gotten the sidepanel tou house fans.
I also got a Sunbeam Rheobus fan controller incoming (20W per channel, 4 channels). And 2 HDD cages (5 disks now, 8 soon).

What I want to do is create a fan setup on this case that provides excellent cooling (because this PC is server-like, 24/7 working), and with the help of the Rheobus, to be able to make it silent when I want to use it.

I am thinking, 8 total fans. These are : 2 on the HDD cages, 1 back, 1 top, 3 on the sidepanel (the 1 slot is blocked by the CPU cooler-scythe mugen) and 1 on the Mugen.

The fan direction is open to debate but not really important at this point because I can change it anytime when I got the fans in hand. What I am thinking is that obviously the back and top fans will be exhausts(because the back fan is exactly behing the scythe thus creating a kind of push-pull scenario), the sidefans will be intakes (to help ditectly cool the GPU and raid5 controller) and then the not so obvious is that I am thinking of using the HDD fans as exhausts too, because their airflow will be blocked 80% anyway by the HDDs, and because the 3 sidefans will provide more than enough incoming fresh air).

But as I said above the direction is not important at this point. Where I want help is which fans to choose. The sidepanel can take 140mm fans so I would like to take advantage of this (not only because of the better noise/cfm ratio but also because they will cover my raid card which is at the bottom better).
So I need 4 x 120mm fans and 3 x 140mm fans.

Preferably I want them to be strong, around 2000rpm+ if possible since I can make them quite with the controller when need be, and if they are not too expensive it's also a good thing, I don't care about leds and stuff.

About the 120mm fans I am not sure but I got some options. The 140mm fans are very tricky though.
The ideal fan would be that Yate loon that hits up to 2800rpm but these things are nowhere to be found. Then I can't find any other 140mm fan with adequate power....the highest I can find is a Koolance with 1700rpm and 92cfm....then a Sharkoon with 1500rpm 82cfm....nothing impressive.

What can you suggest?