Storing important files online is convenient, but it also poses a security risk. Even if your cloud service offers encryption, that won’t necessarily keep your data safe, as if someone manages to obtain your account password then they’ll probably be able to access whatever they like.
If you need real privacy, then, you might want to consider encrypting files before they’re uploaded. This adds a useful extra layer of protection which makes it far more difficult for an attacker to view your files. And it doesn’t have to involve any real extra work, either – the open source CryptSync makes the process almost automatic.