Seasonic M12II Bronze 620
Has a 12cm, ball bearing fan, which is usually the ADDA AD1212MB-A71GL. The fan has been measured spinning between 500-2200RPM.
It is quiet up to about a 300W load.
Thermaltake Smart M550W
It uses a 14cm fan, a Thermaltake branded Yate Loon D14SM-12. According to TT's website it's fan spins between 750-1604RPM, and the noise rating is 21-38.5dBA. However this fan is known for not starting up before 1000RPM, so I don't really believe that 750 number. 21dBA isn't that low of a minimum number either IMO.
There is more than one XFX ProSeries 650W 80 Plus Bronze, there is the Core Edition and there is the XXX Edition.
They are both 13.5cm and use ADDA ADN512UB-A90. The Core Edition's maximum noise level is supposedly 36dBA.
I would say that the Seasonic M12II Bronze is the best choice in terms of noise out of the ones listed, but I would like to know what other options you have. Are you using a particular website to do your shopping?