Would you rather have a power pack or battery case?

[PhiLLoW]

I don't use a case because I really love how thin smartphones have become nowadays.

I was using this easyAcc powerBank with 15000mAH for around 2 years now and I really love it:

http://www.amazon.de/gp/product/B00...&tag=wwwphillownet-21&linkId=EBWDEIK2AEEPRZWN