Personally, I'd recommend you have a physical backup on a spare HD as first priority, then work on some cloud option to open up the files you do want online. I would never rely on the cloud as a sole solution. Especially if you have any personal data to backup.
I've got spare HD's and a USB enclosure so I can backup files and move them as necessary. For portability I've used USB drives, and carried HD's with me. USB flash drives hold a fair bit of stuff these days, and they're really portable. It depends how much file storage you need really.
For off-site backup my ideal for really important stuff would always be in a locked fireproof container at a family house.