What is it that you're after?
The thread title suggests a cpu heat sink/cooler but your post reads more like you're after case fans.
There is no one best fan, because there are different tyoes of fans for different uses/requirements.
The silverstone air penetrator fans are great if you need to push a path of air over a distance, the special grill on the back "shapes" the air vortex of the exhaust of the fan to create a long narrow cone.
Silverstone did a great video to show the effect
http://www.youtube.com/watch?v=8m8fC809TK0
So what this type of fan is good for is as an intake that has to blow air across a relatively open area and at longer distances, eg in the front of a case that does not have hard drive bays or on the back side of hard drive bays, so it can blow that focused cone of air over the motherboard.
As a case exhaust fan or a cpu cooler or radiator fan they are not so good, they are not bad but the air grill is doing nothing for it as you're blowing air into a restricted area (for cpu cooler/rad) or into empty space that doesn't need a narrow cone (case exhaust)
The 2nd factor with them is that they have to run faster to get the air flow up to the speed that the effect occurs, slowing down the fan reduces the effect and the added restriction of the grill actually has a slight negative overall performance of them.
Air flow, speed and noise are generally directly correlated, the faster the fan the more the air flow and the more the noise.
However there are lots of other factors that get mixed in, one of them being that sound is subjective, what you call "too loud" someone else might call "acceptable" and vis versa, on top of that you have background noise, I hardly notice my fans a 6pm on a weekday but I'll notice the noise at 1am on a sunday, the fans are not any louder just the difference in background noise.
Even the placement of your case an the fans within it have an effect.
The Deep Silence 6 comes with 5 low rpm 140mm fans, so I'd suggest giveing them a try first before you consider replacing them, to light it up I think the best bet is to get some LED ribbon lights
http://www.scan.co.uk/products/phoby...nnection-cable and just stick them in.