If you just want air flowing through your case, get the Papst 8412 NGL. It's completely silent and if you have 2 or 3 of them your case circulation will be fine. If you don't feel comfortable (with you shouldn't, I have three 18 CFM NMB case fans and my case temps are only 3 C's higher than ambient room temp) with the papst or if it's too expensive, get the YS-TECH FD8125. It's barely audible (mostly from the sound of air moving). This is all assuming that you need 80 mm fans. If you need 120 mm fans, get the Papst 4412FGL. That moves plenty of air for very little noise. Just remember, once you use quiet fans like these, often other noises that was masked before will now be noticable.
On the topic of your other thread, any of the deltas on your page will be fine. Note thought, at the cost of your ears, you will get some serious cfms moving. I think deltas are way overkill for case and cpu cooling though.