I'll find out about the Panaflos later (see my thread about the bad ones I got), when I get a good batch, but the enermax thermal control fan is a good quiet one, as are the adjustable enermax fans on low. The Vantec Stealth fans aren't bad, but aren't as good as they claim. My 1-year cybercooler ball bearing fan is about as quite as the same size vantec stealth, and they push similar air...wasted money, IMO.
Another good option would the NMB ultra quiet fans. Several websites sell them and CHEAP. They don't push much air, but are quiet and reliable; Dell and other OEMs have used them off and on over the years. I wouldn't trust one on a heatsink, but for a case fan, sure. With a good path for airflow, the cheap NMBs are a great option, IMO.