Also do not forget what many ex-WD owners will complain about: reliability. Regretfully WD external drives have long term reliability issues and, as usual, it will come back to bite you at just the right moment (read: when you usually depend upon it the most). IMHO do not trust a single-drive WD product, only their RAID boxes are even worthy of consideration.
QNAP makes a great product, as well as Synology. I was looking at those but went with LaCie's 2Big NAS and am one absolutely ecstatic customer: 4TB, FTP, SFTP, HTTP, Time Machine, RSync, BitTorrent, DNLA, RAID1 etc etc etc plus full Wuala integration, enabling access via website, private direct DNS link sharing, Android and iPhone. I think what I most love about the box is that it is passively cooled; it is sitting just below my television, eye-visible (as it is so pretty anyway), and I don't think I've *ever* heard any [auxiliary] fan noise .
My WD device dying turned out to be a fantastic opportunity to get some great kit.