Yes, there's no point in just randomly recommending a fan as high fin densities require much higher back-pressures, and the other thing to consider is are they going to use a shroud as this also affects what fans can be deployed in a noise vs. cooling sort of way.
In general though I think Arctic Cooling PWM fans make a lot of sense as they have a daisy-chain function that allows up to 5 fans to be daisy-chained off the CPU fan header. You can then let the motherboard determine if the fans need to run or not.
I have a system with a PA120.3 shrouded with three AC 12025PWM fans daisy-chained off the CPU fan header. The motherboard (Abit IP35-Pro) allows great control of the PWM fans in the BIOS so I have the fans switched off completely until the motherboard CPU temp reaches 40C at which point they come on at 25% (about 400rpm) then if the motherboard temperature reaches 45C they come on at 75% (1200rpm) and in the extremely unlikely case that the motherboard CPU sensor reaches 50C they come on 100% (1600rpm).
Abit and J&W offer excellent control patterns over the CPU fan and Gigabyte pretty much have all the fan headers on their motherboards now as PWM headers, although they don't offer the same level of programmability as Abit.