makes little or no difference as most fans are mislabeled... as either high air flow or static pressure... you need to measure both to see how efficent a fan is...
best you go for high cfm fans for the cpu. and balance the cfm from intake to outflow for the case. with a slight preference on positive case pressure as it will help keep dust levels down...
linus tech for instance says us sp(static pressure) fans for the cpu and af(air flow) for the case. when in fact theres no actual difference in the fans other than 1 runs at 200rpm faster so gives better sp numbers. pure marketing hype for people that dont understand...
if you want good fans you pay for them (noctua nff12/14) if you want quiet you'll pay for them 2(noctua(undervolted)...