If you're looking for just a drive to put your music in and really nothing else, I recommend the Hitachi DeskStar 3TB 5400RPM I just picked up. The WD Green drives seem to die in few months for me.
If you can wait a couple months, Seagate/Samsung is supposed to release a 3-platter 3TB drive. That will be the one to get.
When they are ready. the 3TB disks are just coming out really, the 4TB ones are probably several months to a year plus away. But that's only a guess based on previous disk evolution.When are the 4TB drives coming out?