I'd pick WD6400AAKS (640GB). One of the highest densities/platter ever, this makes it great for handling huge wav files.
Seagate's 7200.11 series is also great but it costs more per GB.
The WD7500AAKS (750GB) is also very fast.
The Samsung Spinpoint F1 1TB is very fast too, but there are some complaints about its reliability.