Uploaded.to : files are deleted for inactivity even if you're premium (over 500GB). Shitty download speeds and limits.
Jumbofiles : Low storage space. Is running on a low margin & probably won't outlast 2012.
ifile : Running on low profit margin, but has been around for many years.. Hopefully it'll be around for a while!
For a backup of your files, you should stick to a host that is likely to be around for a while. Consider if it is safe legally, and consider if it is doing well financially. Also, it's better to stick to older sites than these newer ones...
So everything considered, mediafire would be the best if you have legal content. if not then Rapidshare premium.