Extra Battery or Portable Charger?

Hi everyone, Iv been planning on going on a world trip after Christmas to start of 2014, I seriously cant wait! Ill be visiting 5 countries across the world from Brazil to China and will be testing out my new Nokia Lumia 1020 camera, so stay tuned, ill be posting some of the pictures on Google+ and on this blog.

Anyway iv been looking for something to charge my phone while i travel, a friend suggested me just to buy an extra battery while another advised me to get a portable charger. 

I could easily buy an extra battery for my phone on eBay but is it really efficient? I mean a battery would last me around 12 hours with moderate to heavy use, and with the Lumias 41 pixel camera it would probably be a lot less but there is also the problem with opening up the phone physically and replacing the battery which can be a real pain because it resets the clock on the phone causing my messages and other apps to act funny.

On the other hand iv found a 12,000mAh 'power bank' which is basically just a huge charger which would give me around 5 full charges without the need to open up my phone. Additionally it has 2 charging ports so my friend can also charge her phone at the same time. But the downside of a portable charger is the weight of it and also it may not get through airport security (ill be going through at least 7 different airports).

What do you guys think i should get?