iPad - making it a business tool - part 3

I won't do the subject justice but you will definitely need/want some kind of cloud storage option.  I know iCloud is an Apple product but I have limited experience with it and can't comment either way on it.  However, I have used Dropbox for years and am a HUGE fan of this application.  Some of the features which I love:

• Seamless sync with whatever I put in the MyDrop box folder.  I save it there and it automatically is saved in the "cloud."  If you are like me you have wondered where the "cloud" actually is.   I don't have the answer - which is why I back this file up on a flash drive periodically (I know paranoid).  
• Cross platform accessibility - this means I can access these files on my desktop, my laptop, my iPad, my Android tablet, and my phone  - and changes made at any of these locations automatically updates to the others - I LOVE THIS
• The ability to designate folders and files to share with others.  This allows me to share pictures or projects and keeps everyone up-to-date.

I also use Google Drive for some storage and especially for documents created with Google docs.  This is also handy for sharing files.

There are other cloud storage options and this is not meant to be a review so you do the research and find out which one(s) work best for you - but you should have at least one on your iPad ready to go.

Which is your favorite cloud storage application and why?