to store music, pics, videos, etc
You can use online backup or online storage . It preserve your data online so it's a good solution. You can compare all providers here : [link removed]
hard drive, it is there and has a less chance of being corrupt. internet, things can get hacked, info lost, or a server crash and you loss everything.
i would go with portable hard drive, that way, when your internet is down, your still gonna have all your stuff.
hard drive definitely, online would be a bit risky for me, but if it is easy maybe you could do both?
Off Site Storage is the good techniques by which we can secure our document for long time.