More small fans vs less bigger fans?

[Kishan25]

Im placing 3x120mm intake fan in the front of my case. I dont know if i should put 2x140mm exaust fans on the top or 3x120mm exaust fans?

 

[BrandonYoung]

3x120mm should move more air. This is assuming similar RPM between the 140mm and the 120mm.

Keeping 2x140mm as exhaust would in theory help sustain a positive air pressure within your case, which is desired to minimize dust accumulation (assuming your intakes are filtered).