What product of Desktop that internal drivers should I buy?

The same as title, and my workspace’s environment is following:

  1. I not shutdown as usual as home user, and maybe a week or a month shutdown once.
  2. I will provide a share space for other users in my network.

My PC spec:
MB: Asrock Z68 Extreme 3 Gen 3
CPU: i5-2500K 3.3Ghz (upto 4.6Ghz)
Memory: Kingston Lovo DDR3-1333 4G*2 (upto 1600)
HDD1: Micron Crucial M4 64GB (SSD for operation system)
HDD2: Waiting to Buy 0.0

Welcome to the WD Community. If you want to maximize capacity and low power consumption, I recommend the WD Green hard drives. Check the link below so you can compare with other models. 

Internal Desktop Hard Drives Overview

http://www.wdc.com/en/products/internal/desktop/

I need efficient one, but I don’t know which one, that  Xe, Re, Se, Ae, or black, is suitable.
I think blue maybe not suitable.

Stable> Efficiency> Low Power

personally i only use Black on desktops, and Red in my Synology NAS.  WD Black drive is the best performance, useful to have on all the time, but its by no means low power.  Green’s are cool/quiet and high capacity.

depends if you have power management set on your system, for shares, then you don’t want the drive spinning down too often.  Otherwise go for the Blue (middle of the road). 

If you do a lot of sharing, or large files such as movies/tv shows etc (or re-route your family iTunes library), then you might want to look at a small 2 disk NAS appliance to sit on your home network – DS214 series i recommned from Synology and if you get the model with the disks supplied, just verify its fitted with WD Red’s (usually they are).

So I don’t need to use  Xe, Re, Se, or Ae?
Black is enough !!??

yes I would say so, those other drives are more geared for Enterprise use/users.

the Black units have never let me down yet – i have dozens bought over the years, and they still work, not had one go bad on me yet. 

I have moved up to 1TB Velociraptor (10k spin speed) as my boot drives at home and work now, just wish they did a higher capacity, using 2TB WD Black as secondary drives.

I agree with IainNIX.

Buy Green or Black. All other drives are for special use, that does not suit you according to the specs in your question.

Green for low temperature, low noise, low price.

Black for high speed.