My guess is the MSI Cyclone, they go out of there way to advertise their non-buzzing ferrite chokes and military class components or whatever, but it's just a guess I don't know where you would find research on noise levels of the PCB independent of the coolers.
I have a HIS (kind of the cheapy version as I understand) that it only a couple days old but is super quiet (I was pleasantly surprised). I have not overclocked it, but at 7.7 on the windows experience scale I really don't see the need. I play crysis 1 with eyefinity (4800x900) high settings with no problems and no sound.
Oh, and I only payed $138 from ebay (shipped from newegg)