I use Google Drive, Mediafire and OneDrive for selected files online hosting. I don't use online storage for backup, I use my external hard drive. I use Imgur, Photbucket and ImageShack for image hosting.
I started to utilise OneDrive to store my Portable Apps, so in case I need to wipe the drive the data can be recovered without having to download, extract and re-configure them. Once I login to my Microsoft Account on Windows 8.1, the files/data will be synced for immediate use, these include portable programs such as, CCleaner64, Autoruns, Process Explorer, Rufus etc.
No longer using Google Drive.
Mega Account stores files I don't wish to be synced to my PC. However, I can download the desktop client for easy download from my account.
Been using Acronis True Image during the 2015 beta test. Not bad. Acronis is not free, but not bad. Will see how it shakes out (price-wise) now that it's out of beta. It has some very decent features too.