silent - all quality Fanless psu's are quietest - silverstone, Yesico (ideal for systems under 250w) FSP zen can squeal at higher loads
near silent - semi fanless (hybrid) psu - Zalman HP (great a 50% load - less so above)
Bequite have lesser electrics that some feel are not worth the risk.
high quality fan psu's - enermax 82+, Corsair
duel card gaming only use third option.
Non/light gaming or silent/HTPC system (and you have the money) fanless psu
everything else - 82+, Corsair, Zalman in that order
The SPCR link above is very usefull
Personal I have a 550w Yesico in my near silent (pesky raptor) fanless system.