Hey I just built my first PC, and I am quite disappointing with the case fan quality.
I got the NZXT Phantom 410 and the fans aren´t pushing enough air, I can only feel a little come out the back so I need some new ones.
Just a few things to add since i´m kind of a noob at this:
Silence is essential, no more than 25dBA.
One 140mm and three 120mm.
I would prefer if the 140mm (exhaust) has red LED´s/UV´s
One last thing... It should be on either komplett.se or inet.se ( on inet.se it should be Stockholm, if you go there you will understand.)
casefans are designed to get air flowing gently, not "push air". if they pushed air, you would be constantly drowning in the noise of wind blowing past your fan grills.
Noctua make some of the best fans on the market. aerocool sharks are pretty good fans too. other than that, NZXT fans are actually pretty decent in quality and you'll have to pay big money to get something better.
I agree with tiny voices, don't change fans unless your components are running too hot, or you're going for a new look (color LEDs etc)