when it comes for FANs, I put them into 3 categories.
1, For radiators. (you need decent Static pressure and Flow)
2, For chassis airflow ( high CFM is good enough.)
3, Performance ( Airflow / dB )
please note, many fans has strong CFM but terrible static pressure, it can be easily tell really, fans with fins that have a observable gap inbetween are usually low with static pressure, and fans like GT with nearly no visible gaps are static pressure kings.
however, if you don't mind going PUSH/PULL, then the static pressure problem almost doesn't exist. And all a sudden, you just want to put the best CFM/dB fan on both side for best performance.
for me, in push/pull config:
SlipStream 1900 RPM
Reeven 2000 RPM
Cooljag 2300 RPM
are all awesome fans. However, do know, of the three, except the Reeven that has enough Static pressure to be decent, the other two NEEDS push/pull to be effective. Else you just be blowing wind to a brick wall.