Not worried about price? then noctua are for you. use the blue leds for intake and use noctua for exhaust
NCIX.com - Buy Noctua NF-P12-1300 120MM Ultra Quiet Cooling Fan 1100-1300RPM 63-92M3/H 12.6-19.8DBA Molex - NF-P12-1300 In Canada.
those S-flex 1200RPM fans are a tiny bit louder than the noctuas but its a cheap alternative.
those scythes 1200rpm are close to antec tri cool's medium speed but 2 time quieter.