I have the Greddy Type-S BOV and it is a bit chirpy under normal driving (when still in vacuum) but once you hit the boost, it lets out a mean whoosh. If I could have done it differently, I would have gone for the HKS SSQV because it doesn't leak at idle like the Type-S and most other valves. The idle would be much smoother and the mixture wouldn't be as rich. They are all adjustable, so any would do. It is all a personal preference as to what sounds best to you.

Here is a page where you can hear the different blow off valves: http://www.935motorsports.com/bov.htm.

The clip of the Supra with the Greddy Type-S is the one that sold me on that BOV.

And if you don't even want the noise, you can recirculate the valve back into the intake tract to acheive better spool up and smoother idle.