Free online storage space

There are a variety of free online storage space that you can use. Here are the most popular examples:

Google Drive:
5GB free, up to 16TB with subscription
PC and Mac

DropBox:
2GB free, up to 16TB with subscription
PC and Mac, also available in Linux

Skydrive (Microsoft):
7GB free
PC and Mac

iCloud (Apple)
5GB free
PC and Mac

What is the best storage option?
Here is a nice article that compares all of the Cloud services.

Zoe