I am a huge fan of WD Red Hard Drives and I am using 4 of them in my Synology DiskStation DS413j and they have not been giving me any problems so far.
WD Red hard drives are designed and extensively tested for compatibility under 24×7 operating environment and for the demanding system requirements of home and small office NAS.
WD Red hard drives used to be available in 3.5″ but now Western Digital just announced the availability of WD Red in 2.5″ for the smaller form factor NAS. If you are using Synology NAS, you could also use the 2.5″ hard drives by buying the 2.5″ Disk Holder.
The new WD Red 2.5″ hard drives will comes in 2 versions for now, the 750GB which will be retailing for S$109 and the 1TB version which will be retailing for S$139.
Besides the new WD Red 2.5″ hard drives announcement, Western Digital also announced a new 4TB version for the WD Red 3.5″ hard drives and it will be retailing for S$329.
For comparison, the current prices (as of 7th September 2013) of WD Red 3.5″ hard drives that are listed by Fuwell are 1TB: S$114, 2TB: S$165, 3TB: S$215.

What is your budget? If you have some to spare like SGD$700, get a Synology NAS if not WD Book Live would be good enough.
I would avoid using D-Link Cloud Router as a backup. Personally, I don’t like to gave a single point of failure. If your router fails, chances are your backup will fail too because it is integrated.
WD Book Live is cheap and no frills and might now have those advance features like in Synology NAS. Advanced Features like FTP, web servers, torrenting, etc.
Synology NAS is one of the best NAS maker in the world right now but however it is not cheap.
Good day, Lester Chan
Thanks for your reply.
Just got a WD Mybook Live to try out. Everything look good, except that the transfer rate was rather slow. I google around, and it says that I need a gigabit router/switch to speed it up.
Bless You
KH Tang