I'm gonna ignore the leds for a second, and recommend this fan
. amazingly quiet (only 9dB, compared to the average of 30dB on a computer), so you can stack lots of these w/ no consequence on the sound level.
has your LEDs, and it brags a 20dB noise level, but i think it's gonna be a bit louder w/ that 42CFM (amount of air pushed). either way, it's controlled by the mobo, so you can change the speed around.
has a nice deisgn, w/ two layers of blades. sorry, no leds again, but it pushes nice (37CFM) and is quiet (~20dB).
that's about it from me. i say go for the first one.