I've had an eheim 1250 running my UV sterilizer, the chinese knock off Simplicity DC pump currently running the return to my tank, and a Red Dragon by Royal Exclusiv. The RD DC pump beats them all in terms of noise. The Eheim and Simplicity DC pump have a slight whine to them. However, the eheim is tried and proven, the chinese is an inexpensive option, the Red Dragon is best. It really depends on how much $$ you have on hand.
Order of Silence
Red Dragon>Simplicity DC=Eheim
Order of Price
Simplicity DC>Eheim>Red Dragon
Hope this helps.