I just ordered an H100 to go into my case (which should have enough room for push/pull) so I want to get new fans for it which are much more pleasing to the ear (quiet. So far I have these in mind:

Scythe Gentle Typhoon AP-14
Scythe Gentle Typhoon AP-15
Yate Loon D12SL
Yate Loon D12SM
Cougar CF-V12H (or maybe CF-V12HP if pulse wave is needed)

Quieter is good but obviously I don't want to lose to much performance. I am going to be using it on an Intel I5 2500K and hope to OC it to at least 4.5ghz. Since i'm going to have to purchase 4 fans, obviously the Yate Loons are my first choice since I can get 4 of them for $20 from Petra's, but if the GT or Cougar are much better I'll spring for them. So what is everyone's opinion?

Yate-loon for price and good noise/performance ratio, otherwise GT.

Cougar are "good" too, but not worth it over GT I think.

I would go with Scythe Gentle Typhoons, it seems the best choice for Watercooling / OCing, main reason they are very hard to get, i waited 4 months for mine. I had 6x GT 1850RPM and they not quiet at 12V, but this would be my choice if you were to have a fan controller, else i would go with AP 14 or AP 13, to me the AP 15 are very quiet below 750rpm and inaudible below 550rpm, but they also dont move much air at those rpms. Recapping i would go with GT AP15 but with a fan controller, else a lower rpm GT.