qualities to look for in a fan:
Double Ball Bearing (if it does not explicitly say this, don't risk getting it. Sleeve Bearing fans have a MTBF (mean time between failures) less than half that of DBB fans).
High CFM:Noise ratio.
thats about it, Panaflos are nice, but when I try to turn down my 92mm panaflo, it sounds weird.
Sunons are my fav, personally, Pabst is good, too.
Tt Smartfan is the gaudiest thing I have ever seen, I hate it.