Since the question asked was for cloud backup recommendations, not the value or safety of cloud based backups, I'll try to answer that question.
CrashPlan worked great for me for a couple years. Right now I'm dumping everything into either DropBox or SkyDrive. Both work fine.
I also have a box.net account, but haven't used it yet.
A cloud based backup service that has a mobile client is nice because you can access your files from anywhere. Cloud based backups also protect your files from the theft of your computer & flood/fire in your house.
I keep all my account and password data in multiple cloud services, but it's encrypted. If I have files that for some reason I didn't want exposed to a cloud service, I'd encrypt those with TrueCrypt or something similar.