Have you tried Toshiba hard disks? I replaced my laptop hard disk several years ago with a Toshiba that was fast, quiet, inexpensive, and reliable.

More recently, after my network-storage USB Western Digital issued an error once or twice, I replaced it with a USB 3.0 Toshiba Canvio. It's also fast, quiet, and inexpensive -- plus it has 3x the warranty; WD only gives 1 year.

When I got my MacBook Air this Spring, I picked up a second one for some extra space. Unfortunately, I didn't get around to setting it up for backups before my SSD failed; but I've learned my lesson, my backups are now entirely automated.