You're going to get better advice on tech forums or from reading reviews on Amazon and Newegg.
But to answer your question, I've used Western Digital all my life and have not had a single drive fail on me. But then again, no brand is perfect. As a general rule, it's a good idea to stick with name brands such as WD, Seagate, etc..
Also physical backups are never entirely secure. What if your external drive fails? I would suggest moving your important documents to cloud services such as Dropbox, Google Drive, or Microsoft Skydrive.