the nerd 389 :
I didn't mean to imply that the ML120s belong in the top 5. They're good performers, but have enough issues to cause concern in a lot of builds. Just ask Corsair about using speed control with them. The requirements are as strict as the most problematic of water pumps.
The Silent Wings 3 is more deserving of a place on the list, though. Regarding your particular application, it comes in a high speed and low speed version. All of the PWM models offer reliable control down to the 250 RPM range, and are very consistent from model to model. They're among the few fans out there that offer this wide of a range to work with. The only other ones that come to mind are the iPPC 3000s with a range of 450 to 2800 RPM on average.
It's worth mentioning that the Silent Wings 3 have a very peculiar PWM vs fan speed curve. If you haven't seen it before, it's worth a look:
http://thermalbench.com/2016/09/05/be-quiet-silent-wings-3-120-mm-fan/3/
The low speed models might actually be a perfect fit for targeting 850 RPM as a max in normal situations while still keeping some headroom on tap for stress tests (note: this statement only makes sense after you see the PWM vs RPM curve above).
No I didn't think that you implied that either, just mentioning that if it doesn't break the top 5, i want going to be looking at from 6 on down.
I like the Wings, but aside from good performance at higher rpms, which is outta my target area, we have since stopped using PWM. As you mentioned with Corsair, they are problematic when ganged as Darla explains here:
http://www.overclock.net/t/1506812/the-best-pwm-rad-fans-going-to-be-very-exact-spec-needs/30
With the advent of PWM fan Control PCBs, you can gain all the speed control advantages of PWM w/o any of the disadvantages Cost / low speed clicking or hum). The other thing that figures in, we used to have as many as 5 different case models for users to choose from in each price niche but last few years the list has dwindled because all most are choosing Phanteks ...and when the case comes with 3 - 5 fans *and* a PWM => DC hub that controls them. make sit hard to justify tossing them and getting something else. I am a bit concerned about the price creep on them...tho still at $15 hard to complain... used to jump on the newegg specials when they were $10 each but can only recall 1 or 2 in 2017. Another complaint ... buv them in a box and they come with the rubber mounts ... pre-installed case fans ... no rubber mount, tho if ya call and ask they mail them to ya.
The thing about the Silent Wings twas that it's kinda unusual that the DCV and PWM ones differ so widely which makes the 120 and 140 deliver very close to the same 1ir flow
120 is 1,450 rpm
140 is 1,000
120 HS is 2,200 rpm
140 HS is 1,600
If doing an ITX build, haven't dome one in ages, I'd prolly go for the Silent Wings .. right now I'm anxious to see how Noctuas new low tolerance fans perform ... on paper, they sound great, logic says that the reduced space between shroud and housing should improve things greatly.... whether we actually see that in practice remains to be seen and I hop other vendors follow suit.
The other thing I like about the wings is that the PWM and DCV versions were selling for about the same price. perhaps that's a recognition of the current state of the industry where, since the arrival of fan control PCBs, PWM lost its speed control advantage.